Recording medium, recording method, reproduction method, recording apparatus and reproduction apparatus

ABSTRACT

A recording medium comprising a recording area, the recording area includes a first area and a second area, the first area includes a frame area, the frame area includes an area in which a second synchronization code sequence and at least a portion of data are to be recorded, and the second area includes an area in which a third synchronization code sequence and a fourth synchronization code sequence are to be recorded.

This application is a continuation of U.S. patent application Ser. No.11/759,271 filed Jun. 7, 2007, which is a continuation of U.S.application Ser. No. 11/552,543, filed Oct. 25, 2006, which is acontinuation of U.S. application Ser. No. 10/203,849, filed on Aug. 14,2002, now U.S. Pat. No. 7,158,464 issued Jan. 2, 2007, which is a §371of International Application No. PCT/JP01/11507 filed Dec. 26, 2001, theentire disclosures of which are incorporated herein by reference, and isrelated to co-pending sibling U.S. application Ser. No. 11/552,548 filedon Oct. 25, 2006 and Attorney Docket No. OKUDP0180USD filed May 2, 2008(U.S. application Ser. No. ______).

TECHNICAL FIELD

The present invention relates to an optical disc medium allowing highdensity data recording, and a method and apparatus for recording data onor reproducing data from the optical disc medium.

BACKGROUND ART

Recently, the recording density of optical disc media has been rapidlyincreasing. In the case of optical disc media allowing digital datarecording, data recording, reproduction and management are generallyperformed in units of blocks, each block having a prescribed bytelength. (Such a block will be referred to as a “data block”.) Each datablock is given address information. Data recording and reproduction areperformed with reference to the address information.

For recording data on an optical disc medium, user data such as, forexample, audio, video and computer data to be stored is provided withredundant data such as, for example, an error correction code (paritycode) used for detecting or correcting a data error when the stored datais read. The user data provided with the redundant data is transformedin accordance with a modulation code system suitable to thecharacteristics of recording and reproduction signals for the opticaldisc medium. On the optical disc medium, the post-transformation databit stream is recorded. One known modulation code system which is oftenused for optical disc media is run length limited code.

A run length limited code determines the post-transformation data bitstream so that the number of “0” bits interposed between two “1” bits ina bit sequence is limited to a prescribed number. The number of “0” bitsinterposed between “1” bits will be referred to as a “zero run”. Aninterval (length) between one “1” bit to the next “1” bit in a data bitstream (code sequence) will be referred to as an “inversion interval”.The limitation of the zero run determines the limits, i.e., the maximumvalue and the minimum value, of the inversion interval of a data bitstream. The maximum value will be referred to as a “maximum inversioninterval k” and a “minimum inversion interval d”.

In the case where a data bit stream is recorded on an optical discmedium by mark position recording (PPM: Pit Position Modulation), bit“1” of the data bit stream corresponds to a recording mark, and a zerorun “0” s corresponds to a space. In the case where a data bit stream isrecorded on an optical disc medium by mark length recording (PWM: PulseWidth Modulation), the recording state, i.e., whether a recording markis to be recorded on the optical disc medium or a space is to berecorded, is switched when a “1” bit of the data bit stream occurs. Inthe case of mark length recording, the inversion interval corresponds tothe length of a recording mark or the length of a space.

Accordingly, when, for example, the minimum value of the physical sizeof marks which can be formed on an optical disc medium (such a minimumvalue will be referred to as a “mark unit”) is equal in the markposition recording and the mark length recording, mark positionrecording requires 3 mark units in order to record data of a minimumcode length (3 bits “100” of a data bit stream), but the mark lengthrecording requires only one mark unit.

When a run length limited code having a minimum inversion interval d=2is used, the number of bits per unit length of track of the optical discmedium is larger in the case of the mark length recording than in thecase of the mark position recording. Namely, the recording density ishigher by the mark length recording than by the mark position recording.

In general, when a data bit stream transformed into a modulation code isrecorded on an optical disc medium, a synchronization pattern is ofteninserted into the data bit stream at every prescribed cycle of the databit stream. Such a synchronization pattern performs proper datasynchronization when the data bit stream is read. According to one knowntechnique for inserting the synchronization pattern, a synchronizationpattern including a sequence which does not exist in a modulation codesequence is inserted at the start of an area, referred to as a framearea, having a prescribed byte length.

Among some data formats for recording-type optical disc media which haverecently been put into practice, the DVD-RW data format will be brieflydescribed.

In the DVD-RW data format, address information is arranged by pre-pitswhich are located in a land between two adjacent groove tracks in whichdata is to be recorded. Data is continuously recorded on the groovetracks. An ECC block, which is a minimum unit for data recording andreproduction, includes a plurality of areas, referred to as data frameareas, each having a fixed byte length. A data frame area includes asynchronization information area provided at the start thereof and adata area. Data recording or reproduction is begun and terminated in thedata area in the data frame area which is located at the start of eachECC block. An operation for additionally recording data in an ECC blocknext to the ECC block which has data already recorded therein isreferred to as “linking”. A data frame area corresponding to a positionat which data recording is begun and terminated is referred to as a“linking frame area”.

FIG. 44 shows a data format of a linking position and the vicinitythereof of a conventional DVD-RW. In a DVD-RW, one ECC block includes 16sectors, and one sector includes 26 frame areas. The minimum unit fordata recording is one ECC block. Data recording is begun and terminatedat a data area DATA of a leading frame area (linking frame area) of aleading sector SO of one ECC block. FIG. 44 shows the position at whichdata recording is begun and terminated as “start position of datarecording”. In the example shown in FIG. 44, linking is performed sothat the data recording is terminated at the 16th byte from the start ofthe linking frame area and the data recording is begun between the 15thbyte and the 17th byte from the start of the linking frame area.

In the linking frame area in which the data recording is begun andterminated, data is recorded in a discontinuous manner. Therefore, datarecorded from the linking beginning position (start position) to thenext frame area cannot be read since accurate bit synchronization cannotbe realized. Furthermore, when the low precision of linking causes thelength of the frame area to be larger or smaller than the prescribedlength, or when repeated linking recording in the same frame areadegrades the signal in the frame area, signal reproduction systems forlevel-slicing, PLL or the like become unstable when the data recorded inand in the vicinity of the linking position is reproduced. In the worstcase, there is a possibility that data cannot be read in several frameareas after the linking position. In such a case, error correctioncannot be performed, which possibly generates a reading error. When thepositioning accuracy when performing linking is less than one bit, thepossibility of accurate data reading is increased. However, thetolerance of less than one bit is difficult to realize and thus isimpractical as the recording density of data is increased.

The present invention, in light of the above-described problems, has anobjective of providing a recording medium, a recording method, areproduction method, a recording apparatus and a reproduction apparatusfor allowing stable data recording and reproduction even at a beginningposition and termination position of data recording.

DISCLOSURE OF THE INVENTION

According to one aspect of the invention, a recording medium comprisinga recording area is provided. The recording area includes a first areaand a second area. The first area includes a frame area. The frame areaincludes an area in which a second synchronization code sequence and atleast a portion of data are to be recorded. The second area includes anarea in which a third synchronization code sequence and a fourthsynchronization code sequence are to be recorded.

In one embodiment of the invention, the second synchronization codesequence represents the start of the frame area, the thirdsynchronization code sequence represents the start of the second area,and at least a portion of the fourth synchronization code sequence isused for stably reproducing data.

In one embodiment of the invention, the first area is provided rearwardwith respect to the third area. The second area is provided rearwardwith respect to the first area. The third area includes an area in whicha first synchronization code sequence is to be recorded.

In one embodiment of the invention, at least a portion of the firstsynchronization code sequence is used for stably reproducing data.

In one embodiment of the invention, the third area includes an area inwhich a fifth synchronization code sequence is to be recorded.

In one embodiment of the invention, the fifth synchronization codesequence is used for specifying the start of the first area rearwardthereto.

In one embodiment of the invention, the first area includes a pluralityof frame areas, the first area is divided into fourth areas eachincluding a prescribed number of frame areas, the second synchronizationcode sequence recorded in the frame area located at the start of thefourth area is different from the second synchronization code sequencerecorded in any of the frame areas other than the frame area located atthe start of the fourth area.

In one embodiment of the invention, the second synchronization codesequence recorded in the frame area located at the start of the fourtharea is different by a code distance equal to or greater than 2 from thesecond synchronization code sequence recorded in any of the frame areasother than the frame area located at the start of the fourth area.

In one embodiment of the invention, a length of the fourthsynchronization code sequence is randomly set each time data is recordedon the recording medium.

In one embodiment of the invention, a length of the firstsynchronization code sequence is randomly set each time data is recordedon the recording medium.

In one embodiment of the invention, at least a portion of the fourthsynchronization code sequence is overwritten by a first synchronizationcode sequence recorded when additional data is recorded on the recordingmedium.

According to another aspect of the invention, a method for recordinginformation on a recording medium having a recording area is provided.The method includes the steps of receiving data; recording a firstsynchronization code sequence in the recording area, recording a framein a first area located rearward with respect to the area of therecording area having the first synchronization code sequence recordedtherein, wherein the frame includes a second synchronization codesequence and at least a portion of the received data; recording a thirdsynchronization code sequence in an area rearward with respect to thefirst area; and recording a fourth synchronization code sequence in anarea rearward with respect to the area of the recording area having thethird synchronization code sequence recorded therein.

In one embodiment of the invention, the method further includes the stepof recording a fifth synchronization code sequence in an area of therecording area which is rearward with respect to the area in which thefirst synchronization code sequence is recorded and is forward withrespect to the first area.

In one embodiment of the invention, the first area includes a pluralityof frame areas, the first area is divided into fourth areas eachincluding a prescribed number of frame areas, the second synchronizationcode sequence recorded in the frame area located at the start of thefourth area is different from the second synchronization code sequencerecorded in any of the frame areas other than the frame area located atthe start of the fourth area.

In one embodiment of the invention, the second synchronization codesequence recorded in the frame area located at the start of the fourtharea is different by a code distance equal to or greater than 2 from thesecond synchronization code sequence recorded in any of the frame areasother than the frame area located at the start of the fourth area.

In one embodiment of the invention, the step of recording the firstsynchronization code sequence includes the step of randomly setting alength of the first synchronization code sequence.

In one embodiment of the invention, the step of recording the fourthsynchronization code sequence includes the step of randomly setting alength of the fourth synchronization code sequence.

In one embodiment of the invention, at least a portion of the firstsynchronization code sequence is used for stably reproducing the data.The second synchronization code sequence represents the start of theframe area. The third synchronization code sequence represents the startof a second area including the third synchronization code sequence andthe fourth synchronization code sequence. At least a portion of thefourth synchronization code sequence is used for stably reproducing thedata. The fifth synchronization code sequence is used for specifying thestart of the first area.

In one embodiment of the invention, at least a portion of the fourthsynchronization code sequence is overwritten by the firstsynchronization code sequence, which is recorded when additional data isrecorded on the recording medium.

According to still another aspect of the invention, a method forrecording additional information on a recording medium having arecording area having information recorded therein is provided. Therecording area includes a first area and a second area. The first areaincludes a frame area. The frame area includes an area in which a secondsynchronization code sequence and at least a portion of data arerecorded. The second area includes an area in which a thirdsynchronization code sequence and a fourth synchronization code sequenceare recorded. The method includes the steps of receiving the additionaldata; detecting the third synchronization code sequence; determining arecording beginning position in the recording area based on the positionof the detected third synchronization code sequence; recording a firstadditional synchronization code sequence at the recording beginningposition; recording additional first area data including an additionalframe in an area of the recording area rearward with respect to the areahaving the first additional synchronization code sequence recordedtherein, wherein the additional frame includes a second additionalsynchronization code sequence for identifying the start of theadditional frame and at least a portion of the received additional data;recording a third additional synchronization code sequence in an arearearward with respect to an additional first area having the additionalfirst area data recorded therein; and recording a fourth additionalsynchronization code sequence in an area rearward with respect to thearea having the third additional synchronization code sequence recordedtherein.

In one embodiment of the invention, the method further includes the stepof recording a fifth additional synchronization code sequence in an areaof the recording area which is rearward with respect to the area inwhich the first additional synchronization code sequence is recorded andis forward with respect to the additional first area.

In one embodiment of the invention, at least a portion of the firstadditional synchronization code sequence is used for stably reproducingthe data. The second additional synchronization code sequence representsthe start of the frame area. The third additional synchronization codesequence represents the start of a second area including the thirdadditional synchronization code sequence and the fourth additionalsynchronization code sequence. At least a portion of the fourthadditional synchronization code sequence is used for stably reproducingthe data. The fifth additional synchronization code sequence is used forspecifying the start of the additional first area.

In one embodiment of the invention, the plurality of additional framesare grouped into a plurality of sector data each including a prescribednumber of additional frames, and the second additional synchronizationcode sequence of the additional frame, among the prescribed number ofadditional frames, at the start of each sector data, is different fromthe second additional synchronization code sequence of any of theadditional frames other than the additional frame at the start of eachsector data.

In one embodiment of the invention, the second additionalsynchronization code sequence of the additional frame, among theprescribed number of additional frames, at the start of each sector datais different by a code distance equal to or greater than 2 from thesecond additional synchronization code sequences of any of theadditional frames other than the additional frame at the start of eachsector data.

In one embodiment of the invention, the step of determining therecording beginning position in the recording area includes the step ofrandomly determining the recording beginning position.

In one embodiment of the invention, the step of recording the firstadditional synchronization code sequence includes the step of randomlysetting a length of the first additional synchronization code sequence.

In one embodiment of the invention, the step of recording the fourthadditional synchronization code sequence includes the step of randomlysetting a length of the fourth additional synchronization code sequence.

In one embodiment of the invention, the step of determining therecording beginning position in the recording area includes the step ofdetermining the recording beginning position so that at least a portionof the fourth synchronization code sequence is overwritten by the firstadditional synchronization code sequence.

According to still another aspect of the invention, a recordingapparatus for recording information on a recording medium having arecording area is provided. The recording apparatus includes a receivingsection for receiving data; and a recording section for recording afirst synchronization code sequence in the recording area. The recordingsection records a frame in a first area located rearward with respect tothe area of the recording area having the first synchronization codesequence recorded therein. The frame includes a second synchronizationcode sequence and at least a portion of the received data. The recordingsection records a third synchronization code sequence in an arearearward with respect to a first area. The recording section records afourth synchronization code sequence in an area rearward with respect tothe area of the recording area having the third synchronization codesequence recorded therein.

In one embodiment of the invention, the recording apparatus records afifth synchronization code sequence in an area of the recording areawhich is rearward with respect to the area in which the firstsynchronization code sequence is recorded and is forward with respect tothe first area.

In one embodiment of the invention, the first area includes a pluralityof frame areas, the first area is divided into fourth areas eachincluding a prescribed number of frame areas, the second synchronizationcode sequence recorded in the frame area located at the start of thefourth area is different from the second synchronization code sequencerecorded in any of the frame areas other than the frame area located atthe start of the fourth area.

In one embodiment of the invention, the second synchronization codesequence recorded in the frame area located at the start of the fourtharea is different by a code distance equal to or greater than 2 from thesecond synchronization code sequence recorded in any of the frame areasother than the frame area located at the start of the fourth area.

In one embodiment of the invention, the recording section randomly setsa length of the first synchronization code sequence.

In one embodiment of the invention, the recording section randomly setsa length of the fourth synchronization code sequence.

In one embodiment of the invention, at least a portion of the firstsynchronization code sequence is used for stably reproducing the data.The second synchronization code sequence represents the start of theframe area. The third synchronization code sequence represents the startof a second area including the third synchronization code sequence andthe fourth synchronization code sequence. At least a portion of thefourth synchronization code sequence is used for stably reproducing thedata. The fifth synchronization code sequence is used for specifying thestart of the first area.

In one embodiment of the invention, at least a portion of the fourthsynchronization code sequence is overwritten by the firstsynchronization code sequence, which is recorded when additional data isrecorded on the recording medium.

According to still another aspect of the invention, a recordingapparatus for recording additional information on a recording mediumhaving a recording area having information recorded therein is provided.The recording area includes a first area and a second area. The firstarea includes a frame area. The frame area includes an area in which asecond synchronization code sequence and at least a portion of data arerecorded. The second area includes an area in which a thirdsynchronization code sequence and a fourth synchronization code sequenceare recorded. The recording apparatus includes a recording section forreceiving the additional data; a detection section for detecting thethird synchronization code sequence; a determination section fordetermining a recording beginning position in the recording area basedon the position of the detected third synchronization code sequence; anda recording section for recording a first additional synchronizationcode sequence at the recording beginning position. The recording sectionrecords additional first area data including an additional frame in anarea of the recording area rearward with respect to the area having thefirst additional synchronization code sequence recorded therein, whereinthe additional frame includes a second additional synchronization codesequence for identifying the start of the additional frame and at leasta portion of the received additional data. The recording section recordsa third additional synchronization code sequence in an area rearwardwith respect to an additional first area having the additional firstarea data recorded therein. The recording section records a fourthadditional synchronization code sequence in an area rearward withrespect to the area having the third additional synchronization codesequence recorded therein.

In one embodiment of the invention, the recording section records afifth additional synchronization code sequence in an area of therecording area which is rearward with respect to the area in which thefirst additional synchronization code sequence is recorded and isforward with respect to the additional first area.

In one embodiment of the invention, at least a portion of the firstadditional synchronization code sequence is used for stably reproducingthe data. The second additional synchronization code sequence representsthe start of the frame area. The third additional synchronization codesequence represents the start of a second area including the thirdadditional synchronization code sequence and the fourth additionalsynchronization code sequence. At least a portion of the fourthadditional synchronization code sequence is used for stably reproducingthe data. The fifth additional synchronization code sequence is used forspecifying the start of the additional first area.

In one embodiment of the invention, the plurality of additional framesare grouped into a plurality of sector data each including a prescribednumber of additional frames, and the second additional synchronizationcode sequence of the additional frame, among the prescribed number ofadditional frames, at the start of each sector data, is different fromthe second additional synchronization code sequence of any of theadditional frames other than the additional frame at the start of eachsector data.

In one embodiment of the invention, the second additionalsynchronization code sequence of the additional frame, among theprescribed number of additional frames, at the start of each sector datais different by a code distance equal to or greater than 2 from thesecond additional synchronization code sequences of any of theadditional frames other than the additional frame at the start of eachsector data.

In one embodiment of the invention, the determination section randomlydetermines the recording beginning position.

In one embodiment of the invention, the recording section randomly setsa length of the first additional synchronization code sequence.

In one embodiment of the invention, the recording section randomly setsa length of the fourth additional synchronization code sequence.

In one embodiment of the invention, the determination section determinesthe recording beginning position so that at least a portion of thefourth synchronization code sequence is overwritten by the firstsynchronization code sequence.

According to still another aspect of the invention, a method forreproducing information recorded on a recording medium having arecording area is provided. The recording area includes a first area anda second area. The first area includes a frame area. The frame areaincludes an area in which a second synchronization code sequence and atleast a portion of data are recorded. The second area includes an areain which a third synchronization code sequence and a fourthsynchronization code sequence are recorded. The method includes thesteps of reproducing the third synchronization code sequence;reproducing the fourth synchronization code sequence; reproducing thesecond synchronization code sequence; and reproducing the at least aportion of the data.

In one embodiment of the invention, the second synchronization codesequence represents the start of the frame area, the thirdsynchronization code sequence represents the start of the second area,and at least a portion of the fourth synchronization code sequence isused for stably reproducing the data.

In one embodiment of the invention, the first area is provided rearwardwith respect to the third area, and the second area is provided rearwardwith respect to the first area. The third area includes an area in whicha first synchronization code sequence is recorded. The method furtherincludes the step of reproducing the first synchronization codesequence.

In one embodiment of the invention, at least a portion of the firstsynchronization code sequence is used for stably reproducing data.

In one embodiment of the invention, the third area includes an area inwhich a fifth synchronization code sequence is to be recorded.

In one embodiment of the invention, the fifth synchronization codesequence is used for specifying the start of the first area rearwardthereto.

In one embodiment of the invention, the first area includes a pluralityof frame areas, the first area is divided into fourth areas eachincluding a prescribed number of frame areas, the second synchronizationcode sequence recorded in the frame area located at the start of thefourth area is different from the second synchronization code sequencerecorded in any of the frame areas other than the frame area located atthe start of the fourth area.

In one embodiment of the invention, the second synchronization codesequence recorded in the frame area located at the start of the fourtharea is different by a code distance equal to or greater than 2 from thesecond synchronization code sequence recorded in any of the frame areasother than the frame area located at the start of the fourth area.

In one embodiment of the invention, a length of the fourthsynchronization code sequence is randomly set each time data is recordedon the recording medium.

In one embodiment of the invention, a length of the firstsynchronization code sequence is randomly set each time data is recordedon the recording medium.

In one embodiment of the invention, at least a portion of the fourthsynchronization code sequence is overwritten by the firstsynchronization code sequence recorded when additional data is recordedon the recording medium.

According to still another aspect of the invention, a reproductionapparatus for reproducing information recorded on a recording mediumhaving a recording area is provided. The recording area includes a firstarea and a second area. The first area includes a frame area. The framearea includes an area in which a second synchronization code sequenceand at least a portion of data are recorded. The second area includes anarea in which a third synchronization code sequence and a fourthsynchronization code sequence are recorded. The reproduction apparatusincludes a section for reproducing the third synchronization codesequence; a section for reproducing the fourth synchronization codesequence; a section for reproducing the second synchronization codesequence; and a section for reproducing the at least a portion of thedata.

In one embodiment of the invention, the second synchronization codesequence represents the start of the is frame area, the thirdsynchronization code sequence represents the start of the second area,and at least a portion of the fourth synchronization code sequence isused for stably reproducing the data.

In one embodiment of the invention, the first area is provided rearwardwith respect to the third area. The second area is provided rearwardwith respect to the first area. The third area includes an area in whicha first synchronization code sequence is recorded. The reproductionapparatus further includes a section for reproducing the firstsynchronization code sequence.

In one embodiment of the invention, at least a portion of the firstsynchronization code sequence is used for stably reproducing data.

In one embodiment of the invention, the third area includes an area inwhich a fifth synchronization code sequence is recorded.

In one embodiment of the invention, the fifth synchronization codesequence is used for specifying the start of the first area rearwardthereto.

In one embodiment of the invention, the first area includes a pluralityof frame areas, the first area is divided into fourth areas eachincluding a prescribed number of frame areas, the second synchronizationcode sequence recorded in the frame area located at the start of thefourth area is different from the second synchronization code sequencerecorded in any of the frame areas other than the frame area located atthe start of the fourth area.

In one embodiment of the invention, the second synchronization codesequence recorded in the frame area located at the start of the fourtharea is different by a code distance equal to or greater than 2 from thesecond synchronization code sequence recorded in any of the frame areasother than the frame area located at the start of the fourth area.

In one embodiment of the invention, a length of the fourthsynchronization code sequence is randomly set each time data is recordedon the recording medium.

In one embodiment of the invention, a length of the firstsynchronization code sequence is randomly set each time data is recordedon the recording medium.

In one embodiment of the invention, at least a portion of the fourthsynchronization code sequence is overwritten by a first synchronizationcode sequence recorded when additional data is recorded on the recordingmedium.

According to still another aspect of the invention, a recording mediumincludes a rewritable recording area for recording data; and a recordingarea exclusively used for reproduction, which has user data and specificpurpose data different from the user data recorded therein. Therewritable recording area includes a first area and a second area. Thefirst area includes a frame area. The frame area includes an area inwhich a second synchronization code sequence and at least a portion ofdata are to be recorded. The second area includes an area in which athird synchronization code sequence and a fourth synchronization codesequence are to be recorded. The recording area exclusively used forreproduction includes a plurality of further frame areas, each of whichincludes, recorded therein, a further second synchronization codesequence for identifying the start of the respective further frame areaand at least a portion of the user data, and an area having a furtherthird synchronization code sequence and the specific purpose datarecorded therein. The further third synchronization code sequenceidentifies the start of the specific purpose data.

According to still another aspect of the invention, a method forreproducing specific purpose data recorded on a recording medium isprovided. The recording medium includes a rewritable recording area forrecording data, and a recording area exclusively used for reproduction,which has user data and specific purpose data different from the userdata recorded therein. The rewritable recording area includes a firstarea and a second area. The first area includes a frame area. The framearea includes an area in which a second synchronization code sequenceand at least a portion of data are to be recorded. The second areaincludes an area in which a third synchronization code sequence and afourth synchronization code sequence are to be recorded. The recordingarea exclusively used for reproduction includes a plurality of furtherframe areas, each of which includes, recorded therein, a further secondsynchronization code sequence for identifying the start of therespective further frame area and at least a portion of the user data,and an area having a further third synchronization code sequence and thespecific purpose data recorded therein. The further thirdsynchronization code sequence identifies the start of the specificpurpose data. The method includes the steps of detecting the furtherthird synchronization code sequence, and reproducing the specificpurpose data in response to the detection of the further thirdsynchronization code sequence.

According to still another aspect of the invention, a reproductionapparatus for reproducing specific purpose data recorded on a recordingmedium is provided. The recording medium includes a rewritable recordingarea for recording data, and a recording area exclusively used forreproduction, which has user data and specific purpose data differentfrom the user data recorded therein. The rewritable recording areaincludes a first area and a second area. The first area includes a framearea. The frame area includes an area in which a second synchronizationcode sequence and at least a portion of data are to be recorded. Thesecond area includes an area in which a third synchronization codesequence and a fourth synchronization code sequence are to be recorded.The recording area exclusively used for reproduction includes aplurality of further frame areas, each of which includes, recordedtherein, a further second synchronization code sequence for identifyingthe start of the respective further frame area and at least a portion ofthe user data, and an area having a further third synchronization codesequence and the specific purpose data recorded therein. The furtherthird synchronization code sequence identifies the start of the specificpurpose data. The reproduction apparatus includes a detection sectionfor detecting the further third synchronization code sequence, and areproduction section for reproducing the specific purpose data inresponse to the detection of the further third synchronization codesequence.

According to still another aspect of the invention, a recording mediumincludes a recording area exclusively used for reproduction, which hasuser data and specific purpose data different from the user datarecorded therein. The recording area exclusively used for reproductionincludes a plurality of frame areas, each of which includes, recordedtherein, a second synchronization code sequence for identifying thestart of the respective frame area and at least a portion of the userdata, and an area having a third synchronization code sequence and thespecific purpose data recorded therein. The third synchronization codesequence identifies the start of the specific purpose data.

According to still another aspect of the invention, a method forreproducing specific purpose data recorded on a recording medium isprovided. The recording medium includes a recording area exclusivelyused for reproduction, which has user data and specific purpose datadifferent from the user data recorded therein. The recording areaexclusively used for reproduction includes a plurality of frame areas,each of which includes, recorded therein, a second synchronization codesequence for identifying the start of the respective frame area and atleast a portion of the user data, and an area having a thirdsynchronization code sequence and the specific purpose data recordedtherein. The third synchronization code sequence identifies the start ofthe specific purpose data. The method includes the steps of detectingthe third synchronization code sequence, and reproducing the specificpurpose data in response to the detection of the third synchronizationcode sequence.

According to still another aspect of the invention, a reproductionapparatus for reproducing specific purpose data recorded on a recordingmedium is provided. The recording medium includes a recording areaexclusively used for reproduction, which has user data and specificpurpose data different from the user data recorded therein. Therecording area exclusively used for reproduction includes a plurality offrame areas, each of which includes, recorded therein, a secondsynchronization code sequence for identifying the start of therespective frame area and at least a portion of the user data, and anarea having a third synchronization code sequence and the specificpurpose data recorded therein. The third synchronization code sequenceidentifies the start of the specific purpose data. The reproductionapparatus includes a detection section for detecting the thirdsynchronization code sequence, and a reproduction section forreproducing the specific purpose data in response to the detection ofthe third synchronization code sequence.

According to still another aspect of the invention, a recordingapparatus for additionally recording information on a recording mediumhaving information recorded thereon or for overwriting informationrecorded on the recording medium is provided. The recording mediumincludes at least one second data unit, each of the at least one seconddata unit includes a prescribed number of first data units, each of theprescribed number of first data units includes a plurality of frameareas having a prescribed byte length, a second synchronization codesequence is recorded at the start of at least one frame area among theplurality of frame areas, the recording medium further includes at leastone first frame area for each second data unit, and a thirdsynchronization code sequence is recorded at the start of each of the atleast one first frame area. The recording apparatus includes a firstdetection section for detecting the second synchronization code sequencefrom the second data unit; a third detection section for detecting thethird synchronization code sequence from the second data unit, and arecording beginning timing determination section for determining atiming for beginning the additional recording or the overwriting, usinga detection result obtained by the first detection section and/or adetection result obtained by the third detection section.

According to still another aspect of the invention, a reproductionapparatus for reading information from a recording medium havinginformation recorded thereon is provided. The recording medium includesat least one second data unit, each of the at least one second data unitincludes a prescribed number of first data units, each of the prescribednumber of first data units includes a plurality of frame areas having aprescribed byte length, a second synchronization code sequence isrecorded at the start of at least one frame area among the plurality offrame areas, the recording medium further includes at least one firstframe area for each second data unit, and a third synchronization codesequence is recorded at the start of each of the at least one firstframe area. The reproduction apparatus includes a first detectionsection for detecting the second synchronization code sequence; a thirddetection section for detecting the third synchronization code sequence:and a reproduction beginning timing determination section fordetermining a timing for beginning the reproduction, using a detectionresult of the first synchronization code sequence obtained by the firstdetection section from a second data unit, which is located forward withrespect to a second data unit from which the information is to be read;and/or a detection result of the third synchronization code sequenceobtained by the third detection section from a second data unit, whichis located forward with respect to a second data unit from which theinformation is to be read.

According to still another aspect of the invention, a reproductionapparatus for reading information from a recording medium havinginformation recorded thereon is provided. The recording medium includesat least one second data unit, each of the at least one second data unitincludes a prescribed number of first data units, each of the prescribednumber of first data units includes a plurality of frame areas having aprescribed byte length, a second synchronization code sequence isrecorded at the start of at least one frame area among the plurality offrame areas, the recording medium further includes at least one firstframe area for each second data unit, and a third synchronization codesequence is recorded at the start of each of the at least one firstframe area. The reproduction apparatus includes a level-slicing sectionfor generating level-sliced data by level-slicing a reading signal fromthe recording medium; a first detection section for detecting the secondsynchronization code sequence from the level-sliced data level-sliced bythe level-slicing section; a third detection section for detecting thethird synchronization code sequence from the level-sliced data; and alevel-slicing mode switching section for switching the mode oflevel-slicing of the level-slicing section at a prescribed position inthe at least one first frame area, using a detection result of the firstsynchronization code sequence obtained by the first detection sectionfrom a second data unit, which is located forward with respect to asecond data unit from which the information is to be read; and/or adetection result of the third synchronization code sequence obtained bythe third detection section from a second data unit, which is locatedforward with respect to a second data unit from which the information isto be read.

According to still another aspect of the invention, a reproductionapparatus for reading information from a recording medium havinginformation recorded thereon is provided. The recording medium includesat least one second data unit, each of the at least one second data unitincludes a prescribed number of first data units, each of the prescribednumber of first data units includes a plurality of frame areas having aprescribed byte length, a second synchronization code sequence isrecorded at the start of at least one frame area among the plurality offrame areas, the recording medium further includes at least one firstframe area for each second data unit, and a third synchronization codesequence is recorded at the start of each of the at least one firstframe area. The reproduction apparatus includes a clock generationsection for generating a bit synchronization clock using a signal readfrom the recording medium; a first detection section for detecting thesecond synchronization code sequence using the bit synchronizationclock; a third detection section for detecting the third synchronizationcode sequence using the bit synchronization clock; and a clockreproduction mode switching section for switching the mode of clockreproduction of the clock generation section at a prescribed position inthe at least one first frame area, using a detection result of the firstsynchronization code sequence obtained by the first detection sectionfrom a second data unit, which is located forward with respect to asecond data unit from which the information is to be read: and/or adetection result of the third synchronization code sequence obtained bythe third detection section from a second data unit, which is locatedforward with respect to a second data unit from which the information isto be read.

According to still another aspect of the invention, a recordingapparatus for additionally recording information on a recording mediumhaving information recorded thereon or for overwriting informationrecorded on the recording medium is provided. The recording mediumincludes at least one second data unit, each of the at least one seconddata unit includes a prescribed number of first data units, each of theprescribed number of first data units includes a plurality of frameareas having a prescribed byte length, a second synchronization codesequence is recorded at the start of at least one frame area among theplurality of frame areas, the recording medium further includes at leastone first frame area for each second data unit, a third synchronizationcode sequence is recorded at the start of each of the at least one firstframe area, and a fifth synchronization code sequence is recorded at theend of each of the at least one first frame area. The recordingapparatus includes a first detection section for detecting the secondsynchronization code sequence from the second data unit; a thirddetection section for detecting the third synchronization code sequencefrom the second data unit; a fourth detection section for detecting thefifth synchronization code sequence from the second data unit; and arecording beginning timing determination section for determining atiming for beginning the additional recording or the overwriting, usingat least one of a detection result obtained by the first detectionsection, a detection result obtained by the third detection section, anda detection result obtained by the fourth detection section.

According to still another aspect of the invention, a reproductionapparatus for reading information from a recording medium havinginformation recorded thereon is provided. The recording medium includesat least one second data unit, each of the at least one second data unitincludes a prescribed number of first data units, each of the prescribednumber of first data units includes a plurality of frame areas having aprescribed byte length, a second synchronization code sequence isrecorded at the start of at least one frame area among the plurality offrame areas, the recording medium further includes at least one firstframe area for each second data unit, a third synchronization codesequence is recorded at the start of each of the at least one firstframe area, and a fifth synchronization code sequence is recorded at theend of each of the at least one first frame area. The reproductionapparatus includes a first detection section for detecting the secondsynchronization code sequence; a third detection section for detectingthe third synchronization code sequence; a fourth detection section fordetecting the fifth synchronization code sequence; and a reproductionbeginning timing determination section for determining a timing forbeginning the reproduction, using at least one of a detection result ofthe first synchronization code sequence obtained by the first detectionsection from a second data unit, which is located forward with respectto a second data unit from which the information is to be read; adetection result of the third synchronization code sequence obtained bythe third detection section from a second data unit, which is locatedforward with respect to a second data unit from which the information isto be read; and a detection result of the fourth synchronization codesequence obtained by the fourth detection section from a the second dataunit, which is located forward with respect to a second data unit fromwhich the information is to be read.

According to still another aspect of the invention, a reproductionapparatus for reading information from a recording medium havinginformation recorded thereon is provided. The recording medium includesat least one second data unit, each of the at least one second data unitincludes a prescribed number of first data units, each of the prescribednumber of first data units includes a plurality of frame areas having aprescribed byte length, a second synchronization code sequence isrecorded at the start of at least one frame area among the plurality offrame areas, the recording medium further includes at least one firstframe area for each second data unit, a third synchronization codesequence is recorded at the start of each of the at least one firstframe area, and a fifth synchronization code sequence is recorded at theend of each of the at least one first frame area. The reproductionapparatus includes a level-slicing section for generating level-sliceddata by level-slicing a reading signal from the recording medium; afirst detection section for detecting the second synchronization codesequence from the level-sliced data level-sliced by the level-slicingsection; a third detection section for detecting the thirdsynchronization code sequence from the level-sliced data; a fourthdetection section for detecting the fifth synchronization code sequencefrom the level-sliced data; and a level-slicing mode switching sectionfor switching the mode of level-slicing of the level-slicing section ata prescribed position in the at least one first frame area, using atleast one of a detection result of the first synchronization codesequence obtained by the first detection section from a second dataunit, which is located forward with respect to a second data unit fromwhich the information is to be read; a detection result of the thirdsynchronization code sequence obtained by the third detection sectionfrom a second data unit, which is located forward with respect to asecond data unit from which the information is to be read; and adetection result of the fourth synchronization code sequence obtained bythe fourth detection section from a second data unit, which is locatedforward with respect to a second data unit from which the information isto be read.

According to still another aspect of the invention, a reproductionapparatus for reading information from a recording medium havinginformation recorded thereon is provided. The recording medium includesat least one second data unit, each of the at least one second data unitincludes a prescribed number of first data units, each of the prescribednumber of first data units includes a plurality of frame areas having aprescribed byte length, a second synchronization code sequence isrecorded at the start of at least one frame area among the plurality offrame areas, the recording medium further includes at least one firstframe area for each second data unit, a third synchronization codesequence is recorded at the start of each of the at least one firstframe area, and a fifth synchronization code sequence is recorded at theend of each of the at least one first frame area. The reproductionapparatus includes a clock generation section for generating a bitsynchronization clock using a signal read from the recording medium; afirst detection section for detecting the second synchronization codesequence using the bit synchronization clock; a third detection sectionfor detecting the third synchronization code sequence using the bitsynchronization clock; a fourth detection section for detecting thefifth synchronization code sequence using the bit synchronization clock;and a reproduction mode switching section for switching the mode ofclock reproduction of the clock generation section at a prescribedposition in the at least one first frame area, using at least one of adetection result of the first synchronization code sequence obtained bythe first detection section from a second data unit, which is locatedforward with respect to a second data unit from which the information isto be read; a detection result of the third synchronization codesequence obtained by the third detection section from a second dataunit, which is located forward with respect to a second data unit fromwhich the information is to be read; and a detection result of thefourth synchronization code sequence obtained by the fourth detectionsection from a second data unit, which is located forward with respectto a second data unit from which the information is to be read.

Hereinafter, a function of the present invention will be described.

In a recording medium according to the present invention, a recordingarea includes a first area and a second area. The first area includes aframe area. In the frame area, a second synchronization code sequenceand at least a portion of data are recorded. The second area includes anarea in which a third synchronization code sequence and a fourthsynchronization code sequence area to be recorded. On such a recordingmedium, additional data recording (linking) can be begun, regarding aposition in the fourth synchronization code sequence as the beginningposition. Thus, additional data recording is not performed in the framearea in which data is recorded. Therefore, data recording andreproduction can be stably performed even at the beginning position andthe termination position of the data recording.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top view of a recordable optical disc medium (recordingmedium) 101 according to a first example of the present invention.

FIG. 2 shows a data format of a data blocks 103 of the optical discmedium 101.

FIG. 3 shows an example of a pattern to be recorded in a firstsynchronization area PA (PA pattern), which is especially preferable inthe first example of the present invention.

FIG. 4 shows an example of a pattern to be recorded in a secondsynchronization area VFO (VFO pattern), which is especially preferablein the first example of the present invention.

FIG. 5 shows an exemplary pattern to be recorded in the secondsynchronization area VFO when Tmin=3 and Tmin=2.

FIG. 6 shows an example of a pattern to be recorded in a thirdsynchronization area SY (SY pattern), which is especially preferable inthe first example of the present invention.

FIG. 7A shows an exemplary recording pattern of a beginning position ofa usual frame area (i.e., second frame area) in the first example of thepresent invention.

FIG. 7B shows an exemplary recording pattern of a beginning position ofa linking frame area (i.e., first frame area) in the first example ofthe present invention.

FIG. 8 shows a top view of a recordable optical disc medium (recordingmedium) 3101 according to a second example of the present invention.

FIG. 9 shows an example of a data format of the optical disc medium 3101in the second example of the present invention.

FIG. 10 shows an example of synchronization code sequences located atthe start of each of the 26 frame areas included in a sector 3103 (FIG.9).

FIG. 11 shows an example of a pattern preferably used as asynchronization code sequence in the second example of the presentinvention.

FIG. 12 shows a specific example of an SY0 pattern and an SY pattern inthe second example of the present invention.

FIG. 13 schematically shows code distances between various types ofsynchronization code sequences (patterns).

FIG. 14 shows an exemplary internal structure of a frame area F0.

FIG. 15 shows specific examples of an SY0 pattern, an SY pattern, and aPA pattern in the second example of the present invention.

FIG. 16 shows other specific examples of an SY0 pattern, an SY pattern,and a PA pattern in the second example of the present invention.

FIG. 17 shows another example of synchronization code sequences locatedat the start of each of the 26 frame areas included in a sector 3103(FIG. 9).

FIGS. 18A through 18D show examples in which synchronization codesequences to be recorded in second frame areas included in one sectorare arranged in the order in which the synchronization code sequencesare recorded on an optical disc medium.

FIGS. 19A through 19C show examples in which synchronization codesequences to be recorded in second frame areas included in one sectorare arranged in the order in which the synchronization code sequencesare recorded on an optical disc medium.

FIG. 20 shows still another example in which synchronization codesequences to be recorded in second frame areas included in one sectorare arranged in the order in which the synchronization code sequencesare recorded on an optical disc medium.

FIG. 21 shows still another example of synchronization code sequenceslocated at the start of each of the 26 frame areas included in a sector3103 (FIG. 9).

FIGS. 22A through 22C show examples in which synchronization codesequences to be recorded in second frame areas included in one sectorare arranged in the order in which the synchronization code sequencesare recorded on an optical disc medium, when four types of patterns SY0,SY1, SY2 and SY3 are used.

FIG. 23 shows a top view of a recordable optical disc medium 401according to a third example of the present invention.

FIG. 24 shows a data format of the data blocks 403 of the optical discmedium 401 (FIG. 23) according to the third example of the presentinvention.

FIG. 25 shows an example of a pattern to be recorded in the fourthsynchronization area PS (PS pattern), which is especially preferable inthe third example of the present invention.

FIG. 26 shows another example of a pattern to be recorded in the fourthsynchronization area PS (PS pattern), which is especially preferable inthe third example of the present invention.

FIG. 27 shows still another example of a pattern to be recorded in thefourth synchronization area PS (PS pattern), which is especiallypreferable in the third example of the present invention.

FIG. 28 shows still another example of a pattern to be recorded in thefourth synchronization area PS (PS pattern), which is especiallypreferable in the third example of the present invention.

FIG. 29 shows still another example of a pattern to be recorded in thefourth synchronization area PS (PS pattern), which is especiallypreferable in the third example of the present invention.

FIG. 30 shows still another example of a pattern to be recorded in thefourth synchronization area PS (PS pattern).

FIG. 31 shows still another example of a pattern to be recorded in thefourth synchronization area PS (PS pattern).

FIG. 32 shows a top view of a recordable optical disc medium 701according to a fourth example of the present invention.

FIG. 33 shows a data format of data blocks 703 of the optical discmedium 701 according to the fourth example of the present invention.

FIGS. 34A and 34B show other examples of the structure of a first framearea 801 a in the fourth example of the present invention.

FIG. 35 shows a top view of a recordable optical disc medium 1001according to a fifth example of the present invention.

FIG. 36 shows a data format of data blocks 1003 a included in areproduction-only area 1004 of the optical disc medium 1001 in the fifthexample of the present invention.

FIG. 37 shows a data format of data blocks 1003 b included in arewritable area 1005 of the optical disc medium 1001 in the fifthexample of the present invention.

FIG. 38 shows a structure of an information recording apparatus(recording apparatus) 1710 according to a sixth example of the presentinvention.

FIG. 39 shows an example of an internal structure of a pattern detectionand synchronization section 1703.

FIG. 40 shows another example of an internal structure of a patterndetection and synchronization section 1703.

FIG. 41 shows the relationship between a data format of the optical discmedium 3101 and the position information.

FIG. 42 shows a structure of an information reproduction apparatus(reproduction apparatus) 1810 according to a seventh example of thepresent invention.

FIG. 43 shows operating waveforms of various timing signals used forreproducing data recorded in and in the vicinity of the first frame areaLF corresponding to the linking frame.

FIG. 44 shows a data format of a linking position and the vicinitythereof of a conventional DVD-RW.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described by way ofillustrative examples with reference to the attached drawings. In thisspecification, the terms “start” and “end” refer to the relativepositions along information tracks of an optical disc medium. A positionat which data is first recorded or reproduced in a zone along aninformation track will be referred to as the “start” of the zone (or thestart of the data recorded in the zone), and a position at which data islast recorded or reproduced in a zone along an information track will bereferred to as the “end” of the zone (or the end of the data recorded inthe zone). In the case where there are area A and area B along aninformation track and data recording or reproduction is performed inarea A after area B, area A is expressed as being “rearward” withrespect to area B, and area B is expressed as being “forward” withrespect to area A. The expression that one area is “rearward” or“forward” with respect to the other area does not necessarily mean thatthe two areas are adjacent to each other. When area A is rearward withrespect to area B and the area A is adjacent to area B, area A isexpressed as being an area immediately subsequent to area B.

In this specification, the term “frame area” represents a specific areaon an information track of an optical disc medium. In the frame area, aprescribed amount of data and/or a prescribed amount of code sequence isrecorded. Data or a code sequence recorded in the frame area is referredto as a “frame”. In this specification, the term “sector” alsorepresents a specific area on an information track of an optical discmedium, and includes a plurality of frame areas mentioned above.

EXAMPLE 1

FIG. 1 shows a top view of a recordable optical disc medium (recordingmedium) 101 according to a first example of the present invention. On arecording surface of the optical disc medium 101, a recording track 102(recording area) is formed in a spiral manner. The recording track 102is divided into data blocks 103. In other words, on the recordingsurface of the optical disc medium 101, the data blocks 103 arecontinuously arranged in a circumferential direction to form theinformation track 102.

FIG. 2 shows a data format of the data blocks 103 of the optical discmedium 101. As shown in FIG. 2, each data block 103 includes a firstframe area 201 at the start thereof and then a plurality of second frameareas 202 thereafter. The first frame area 201 and the second frameareas 202 form one data block 103. In FIG. 2, an area shown in the rightis rearward to an area shown in the left.

Thus, the information track 102 of the optical disc medium 101 includesa plurality of second frame areas 202 (collectively referred to as afirst area) and a first frame area 201 (second area) which are includedin one data block.

The first frame area 201 includes a first synchronization area PA at thestart thereof and then a second synchronization area VFO thereafter.

The second frame area 202 (frame area) includes a third synchronizationarea SY at the start thereof and then a data area DATA thereafter. Athird synchronization area SY is an area in which an SY pattern (secondsynchronization code sequence) is to be recorded. A data area DATA is anarea in which at least a portion of user data to be recorded in therecording medium is to be recorded. In other words, the second framearea 202 (frame area) includes an area in which an SY pattern (secondsynchronization code sequence) and at least a portion of the user dataare to be recorded.

The role of each area will be described. First, the data area DATA isfor recording a data bit stream including user data. The data bit streamincludes a parity code used for detecting or correcting a data errorwhen the data is read. The parity code is included in an area other thanthe user data. The data bit stream is not recorded as binary dataitself, but is transformed by a modulation system matching thecharacteristics of a recording and reproduction signal of the opticaldisc medium before being recorded.

Here, it is assumed that a post-transformation data bit stream is a codesequence limited to the minimum run (minimum inversion interval) d andthe maximum run (maximum inversion interval) k, and the code sequence isobtained by dividing the input data bit stream into blocks each havingunits of (m×i) bits and then transforming each block of the input datainto a code sequence having units of (n×i) bits. In this case, d and kare each a natural number fulfilling d<k, m and n are each a naturalnumber fulfilling m<n, and i is a natural number fulfilling 1≦i≦r.Especially when r=1, this transformation system is referred to as afixed length code system, and when r≧1 (i can be a plurality of values),this transformation system is referred to as a variable length codesystem.

When a code sequence is recorded by the NRZ (Non Return to Zero) format,bit “1” of the code sequence corresponds to a recording mark and a zerorun “0” s corresponds to a space. In an optical disc medium, recordingmarks and spaces are distinguished from each other by whether the pitsare convex or concave or by a difference in reflectance which is causedby a phase change in a recording layer. When the code sequence isrecorded by the NRZI (Non Return to Zero Inverted) format, the recordingstate, i.e., whether a recording mark is to be recorded or a space is tobe recorded, is switched when a “1” bit of the data bit stream occurs.In the case of mark length recording, the inversion interval correspondsto the length of a recording mark or the length of a space.

Assuming that the minimum value of the size of marks which can be formedon a recording layer of an optical disc medium (such a minimum valuewill be referred to as a “mark unit”) is equal in the NRZ recording andthe NRZI recording, the NRZ recording requires 3 mark units in order torecord data of a minimum code length (3 bits “100” of a data bitstream), but the NRZI recording requires only one mark unit.Accordingly, when a run length limited code having a minimum inversioninterval d=2 is used, the number of bits per unit length of track of theoptical disc medium is larger in the case of the NRZI recording than inthe case of the NRZ mark recording. Namely, the recording density ishigher by the NRZI recording than by the NRZ recording.

In the first example of the present invention, mark length recording isperformed using a run length limited code having parameters of d=2,k=10, m=8, n=16, and r=1 for modulation. In other words, the data bitstream recorded in the data area DATA of the optical disc medium 101(FIG. 1) includes recording marks and recording spaces having a minimumlength Tmin=3 bits and a maximum length Tmax=11 bits.

The first synchronization area PA is provided for identifying the startof the first frame area 201, and preferably has a pattern recorded whichdoes not occur in a data bit stream to be recorded in at least the dataarea DATA. By recording a pattern in the first synchronization area PA,which does not occur in the data area DATA, the first synchronizationarea PA can be easily distinguished from the data area DATA when thedata bit stream is read.

The second synchronization area VFO is provided for realizing stableoperations of data reproduction systems when each data block 103 isread. The data reproduction systems refers to, for example, a sectionfor level-slicing a reproduction signal RF (Radio Frequency) read fromthe data block 103 and a PLL (Phase Locked Loop) section for extractinga bit synchronization clock from the level-sliced data. In order torealize stable operations of the data reproduction systems, the patternsrecorded in the second synchronization area VFO preferably fulfillconditions 1 through 3 given below.

(Condition 1) A sufficient amplitude and a sufficient S/N ratio (Signalto Noise Ratio) of the reproduction signal RF are guaranteed.

(Condition 2) The number of times of recording mark/space switching issufficient.

(Condition 3) The DSV value (Digital Sum Value) of the pattern is asclose to 0 as possible.

Condition 1 is for properly obtaining level-sliced data from thereproduction signal RF. When the amplitude of the reproduction signal RFis too small or the S/N ratio thereof is too low, the signal is notaccurately level-sliced or the signal is level-sliced into wrong datadue to the influence of the noise of the data reproduction systems.

Condition 2 is for obtaining a bit synchronization clock from thelevel-sliced data at a high speed and stably. When the clockfrequency/phase is locked by the PLL section in the secondsynchronization area VFO, the information for frequency/phase comparisoncan be obtained more frequently as the number of times of recordingmark/space switching is larger. Thus, the clock frequency/phase can belocked more quickly. When the number of times of recording mark/spaceswitching is too small, the information for frequency/phase comparisoncannot be obtained. As a result, clock frequency/phase is locked moreslowly or unstably.

Condition 3 is for stably level-slicing the reproduction signal RF. Inthe case where a DC feedback system (for performing feedback control ofslicing level by a DC component of the post-level-slicing data), whichis generally used as a level-slicing system, is used, when the DSV valueof the pattern significantly fluctuates or disperses, the slicing levelsignificantly fluctuates or significantly shifts from the center of thereproduction signal RF. As a result, the level-sliced data cannot bestably obtained. A DSV value of the pattern which is as close aspossible to 0 is preferable to the DC feedback system.

The third synchronization area SY is provided for identifying the startof each second frame area 202. Like the first synchronization area PAfor identifying the start of the first frame area 201, it is preferableto record a pattern, in the third synchronization area SY, which doesnot occur in at least a data bit stream to be recorded in the data areaDATA. By recording a pattern, in the third synchronization area SY,which does not occur in the data area DATA, the third synchronizationarea SY can be easily distinguished from the data area DATA when thedata bit stream is read.

FIG. 3 shows an example of a pattern to be recorded in the firstsynchronization area PA (PA pattern), the example being especiallypreferable in the first example of the present invention. A feature ofthe PA pattern shown in FIG. 3 is that the pattern includes a recordingmark or a space having a length of 14 channel bits (14T), which is a(Tmax+3) channel bit length. In the first example, as described above,the maximum mark/space length Tmax of a data bit stream to be recordedin the data area DATA is 11 channel bits (11T), which is different, by 3bits, from 14T included in the first synchronization area PA. Even whena 1 channel bit edge shift occurs due to the influence of noisegenerated during reproduction, and as a result, the 14T mark (or the 14Tspace) in the first synchronization area shortens to 13 channel bits andthe 11T mark (or the 11T space) in the data area DATA lengthens to 12channel bits, there is still a 1 channel bit difference between the mark(or space) in the first synchronization area and the mark (or space) inthe data area DATA. Thus, against an edge shift of about one bit, asufficient error margin is provided for preventing the 11T pattern inthe data area DATA from being incorrectly detected as the pattern in thefirst synchronization area PA. In this manner, the PA pattern is usedfor identifying the start of the subsequent VFO pattern.

In the example shown in FIG. 3, a 4T space/mark is located immediatelyafter the 14T mark/space. By using (14T+4T) as the detection patternwhen the data in the data block 103 is read, the possibility ofincorrect detection can be reduced compared to using only 14T as thedetection pattern. By adding (15T+3T) or (13T+5T) to the detectionpattern, not only (14T+4T), 14T can be avoided from being undetectedeven when an edge shift occurs at the rear end of the 14T, and still thepossibility of incorrect detection can be kept as low as possible.

Thus, a PA pattern can be easily distinguished from the VFO patternrearward thereto or any other pattern recorded in the data area DATA. Bythe reproduction apparatus or the recording apparatus detecting the PApattern, it becomes possible to determine the termination of the dataarea DATA in a data block forward with respect to the PA pattern, or topredict the start of the second synchronization area VFO subsequent tothe PA pattern or the start of the data block rearward to the secondsynchronization area VFO. Specific examples in which the PA patternrecorded in the first synchronization area is used for reproductioncontrol or recording control will be described later in sixth andseventh examples. The PA pattern represents the start of the first framearea (second area).

In FIG. 3, the pattern in the first synchronization area PA isrepresented by the NRZ format as {1001001001000100000000000010001}. Byadding, to immediately before (14T+4T), the sequence (3T+3T+3T+4T)fulfilling the run length limitation of d=2 and k=10 (limitation on thezero run, i.e., the number of continuous “0” bits) as in the case of themodulation code, a pattern of having a total of 32 channel bits (i.e., 2bytes) is formed. It is preferable that the sequence located immediatelybefore 14T fulfills the same run length limitation as that of themodulation code, but the present invention is not limited to this. Thepattern of the first synchronization area PA is not limited to onepattern, but can be selected from a plurality of patterns. For example,a plurality of patterns having different zero runs (the number ofcontinuous “0” bits) at the start of the pattern is prepared. From theplurality of patterns, one pattern is selected so that the selectedpattern fulfills the same run length limitation as that of themodulation code when being connected to the zero run resulted from themodulation of the immediately preceding byte (final zero run).Alternatively, a plurality of patterns having different DSV values, andone pattern is selected so that the post-selection DSV value is minimum.The post-selection DSV value is a sum of the DSV value of the sequenceimmediately preceding the selected pattern and the DSV value of theselected pattern.

FIG. 4 shows an example of a pattern to be recorded in the secondsynchronization area VFO (VFO pattern), the example being especiallypreferable in the first example of the present invention. A feature ofthe VFO pattern shown in FIG. 4 is that the pattern includes repeated 4channel bit recording marks and spaces. The pattern shown in FIG. 4fulfills conditions 1 through 3 as described above.

The pattern having a single length of 4T guarantees a sufficientamplitude of the reproduction signal RF (condition 1). A pattern whichprovides the largest number of times of mark/space switching is apattern having a single length of 3 channel bits (minimum length), but apattern having a single length of 4T is considered as preferable for thefollowing reason. In the recording and reproduction characteristics ofan optical disc medium realizing high density recording, the amplitudeof a reproduction signal RF having a minimum length bit is generallysignificantly shorter than the longer mark/space. Therefore, with thelength of 3 channel bits, a reproduction signal RF to be stablylevel-sliced may not be obtained. Therefore, a pattern having a singlelength of 4T is considered as preferable in order to fulfill bothconditions 1 and 2. Since the pattern having a single length of 4T canhave the DSV=0, the pattern also fulfills condition 3.

The pattern to be recorded in the second synchronization area VFO is notlimited to a pattern having a single length of 4T. It is preferable torecord a pattern fulfilling all the conditions 1 through 3, but theconditions can be provided with priority levels in accordance with therecording and reproduction characteristics of the optical disc medium.For example, in the case of an optical disc medium which provides asufficient amplitude of a reproduction signal RF (condition 1) with arecording mark or space having a minimum length of 3T, a pattern havingrepeated 3T recording marks or spaces can be used. Thus, the number oftimes of mark/space switching can be increased (condition 2) as comparedto a pattern having a single length of 4T. In this manner, condition 2obtains a higher priority level than condition 1, and the data PLL canbe locked more quickly. Alternatively, in the case of an optical discmedium which does not provide a sufficient amplitude of a reproductionsignal RF even with a pattern having a single length of 4T, a patternhaving repeated 5T recording marks or spaces can be used. In this case,condition 1 obtains a higher priority level than condition 2; i.e.,although the number of times of mark/space switching is decreased ascompared to a pattern having a single length of 4T, the precision ofdata level-slicing can be improved.

FIG. 5 shows an exemplary pattern to be recorded in the secondsynchronization area VFO when Tmin=3 and Tmin=2. In the example shown inFIG. 5, when Tmin=3, a pattern having repeated 4T recording marks andspaces is used; and when Tmin=2, a pattern having repeated 3T recordingmarks and spaces is used.

Thus, a pattern having a single length of (Tmin+1) channel bits providesa sufficient amplitude of a reproduction signal RF and thus fulfillscondition 1.

When an 8/16 modulation system is used, Tmin=3 and 1 byte=16 channelbits. Therefore, 4T marks or spaces are repeated 4 times per byte. Sincethe length of the second synchronization area VFO in the first exampleis 91 bytes, 4T marks or spaces are repeated 364 times (=91×4).

The 8/16 modulation system is one system for transforming 8 bit binarydata into a code word having 16 channel bits. The 8/16 modulation systemis disclosed in detail in, for example, Japanese Laid-Open PublicationNo. 8-31100. In the 8/16 modulation system, a plurality oftransformation tables are allocated to 8 bit pre-modulation data, andthe transformation tables are switched to transform the 8 bitpre-modulation data into a code so that the post-modulation codesequence has as few low frequency components as possible. Thetransformation tables are switched so that the conditions of the minimuminversion interval d=2 and the maximum inversion interval k=11 arefulfilled while minimizing the absolute value of the DSV in the codesequence.

FIG. 6 shows an example of a pattern to be recorded in the thirdsynchronization area SY (SY pattern), the example being especiallypreferable in the first example of the present invention. A feature ofthe SY pattern shown in FIG. 6 is that the pattern includes a recordingmark or a space having a length of 14 channel bits (14T), which is a(Tmax+3) channel bit length. The length of 14T is different by 3 channelbits from the maximum mark/space length Tmax of 11 (11T) of a data bitstream to be recorded in the data area DATA. Therefore, against an edgeshift of about one bit, a sufficient error margin is provided forpreventing the 11T pattern in the data area DATA from being incorrectlydetected as the pattern in the third synchronization area SY, asdescribed above regarding the pattern to be recorded in the firstsynchronization area PA with reference to FIG. 3. In this manner, the SYpattern is used for identifying (or representing) the start of thesecond frame area 202 (frame area).

A method for recognizing an absolute position (hereinafter, referred toas an “address”) in the information track 102 from the optical discmedium 101 in the first example of the present invention will bedescribed. In order to record data at a prescribed address on arecordable optical disc medium, a recording apparatus needs to readinformation on the prescribed address before data recording and searchfor the position at which the data is to be recorded. In order to obtainaddress information in an area where no data has been recorded, theaddress information needs to be pre-formatted. According to an exemplarypre-formatting technique, the address information is represented bypre-pits defined using the convex and concave portions at the recordingsurface, or the address information is represented by the manner ofmeandering in which grooves for forming the information track 102 areformed.

In the present invention, any technique can be used for obtaining theaddress information in the optical disc medium 101. Unless specificallydescribed in this specification, each data block is given inherentaddress information, and the address information of each data block isobtained by accessing a prescribed portion of the information track 102.

With reference to FIG. 2 again, a method for recording data on theoptical disc medium 101 (FIG. 1) having the above-described data formatwill be described. On the optical disc medium 101, data is recordedusing the data block 103 as a minimum unit. A series of data recordingis begun and terminated in the second synchronization area VFO of thefirst frame area 201. Herein, the first frame area 201 including aposition at which data is additionally recorded is referred to as a“linking frame area”.

When additional data is recorded from the termination position of aseries of data recording, the beginning position of the additional datarecording and the termination position of the additional data recordingare determined so that the relationship S≦E is always fulfilled with thefollowing conditions. The beginning position of the additional datarecording is an Sth byte of the second synchronization area VFO of thefirst frame area 201, which is a linking frame area (“S” is a rationalnumber which is smaller than the number of bytes representing the lengthof the second synchronization area VFO). The termination position of theadditional data recording is an Eth byte of the second synchronizationarea VFO (“E” is a rational number which is smaller than the number ofbytes representing the length of the second synchronization area VFO).By thus determining the beginning position and termination position ofthe additional data recording, the portion in which the data isadditionally recorded includes no area which is left without any pattern(VFO pattern) recorded. When an area is left without any VFO patternrecorded, there is an undesirable possibility that the reproductionsystems are not accurately locked.

The difference between S and E is preferably determined in considerationof various fluctuation error factors of a driving apparatus. In an idealstate where the fluctuation error is zero, the number of bytes given by(S−E) is recorded in the same area when recording of data is terminatedand also when recording is begun. Therefore, the data previouslyrecorded in this area is overwritten by data currently recorded.Accordingly, it is preferable to set the number of bytes given by (S−E)to be the upper limit of the fluctuation error factors or higher. Inthis case, even when the fluctuation error is maximum, additional datarecording can be performed without leaving any area without any VFOpattern recorded.

When the optical disc medium 101 is a rewritable optical disc mediumformed using a phase change recording material or the like, repeatingadditional data recording a great number of times at the same positionmay cause degradation of the recording layer. In order to minimize thedegradation of the recording layer and still improve overwritability(increase the number of times data can be recorded on the same track),the beginning position and the termination position of data recordingcan be randomly changed within a prescribed range each time data isrecorded. In such a case, the length of the first frame area 201 is notnecessarily a fixed byte length. The reason is that the length of thesecond synchronization area VFO varies due to the change of thebeginning position and the termination position of data recording. Howmuch the beginning position and the termination position of datarecording should be changed is preferably determined in consideration ofthe length of the second synchronization area VFO, the time periodrequired for locking the reproduction systems, the degradationcharacteristics of the recording layer, and the like.

According to the present invention, the frame area in which additionaldata recording is begun, i.e., the linking frame area, is the firstframe area 201 which does not include a data area DATA. Therefore, evenadditional data recording is not performed discontinuously. Accordingly,the undesirable possibility is eliminated that additionally recordeddata is not read and as a result, data recorded in one frame area islost. As compared to the conventional optical disc medium in whichlinking is performed in a data area DATA (additional data is recorded inthe data area DATA), the reading error margin in the additionallyrecorded data can be significantly improved. As a result, data recordingand reproduction can be stably performed even at the beginning positionand the termination position of data recording.

As can be appreciated from FIG. 2, a recording apparatus records data onthe optical disc medium 101 as follows. First, a record start VFOportion 2102 (first synchronization code sequence provided for stablyreproducing data) shown in FIG. 2 is first recorded in the first framearea 201 (third area) on the information track 102, and then the atleast one second frame area 202 is recorded. Accordingly, the area(first area) in which at least one second frame is rearward to the firstframe area 201 (third area). The first frame area 201 (third area)includes an area in which a record start VFO portion 2102 (firstsynchronization code sequence) is to be recorded.

The second frame area 202 includes the SY pattern (secondsynchronization code sequence) for identifying the start of the secondframe area 202 and at least a portion of the data to be recorded (datato be recorded in the data area DATA). In the case where the data to berecorded on the optical disc medium 101 corresponds to a plurality ofdata blocks 103, the first frame area 201 is provided at the border oftwo adjacent data blocks 103 so that the PA pattern and the VFO patternare recorded. When the data recording on the optical disc medium 101 isterminated, a PA pattern (third synchronization code sequence) isrecorded after the at least one second frame area 202. Then, a recordfinish VFO portion 2101 (fourth synchronization code sequence providedfor stably reproducing data) shown in FIG. 2 is recorded. The PA patternand the record finish VFO portion 2101 are recorded in a first framearea 201 (second area). This first frame area 201 (second area) isdifferent from the first frame area 201 (third area) in which the recordstart VFO portion 2102 was recorded when the recording was begun, and isprovided rearward to the first area. The first frame area 201 (secondarea) includes an area in which the PA pattern (third synchronizationcode sequence) and the record finish VFO portion 2101 (fourth area) areto be recorded.

In order to randomly change the beginning position of the additionalrecording, the length of the record start VFO portion 2102 (the firstsynchronization code sequence provided for stably reproducing data)shown in FIG. 2 in the VFO pattern may be randomly set. In order torandomly change the termination position of the additional recording,the length of the record finish VFO portion 2101 (the fourthsynchronization code sequence provided for stably reproducing data)shown in FIG. 2 in the VFO pattern may be randomly set. When thebeginning position or the termination position of recording is randomlychanged, it is not indispensable that the length of the record finishVFO portion 2101 or the record start VFO portion 2102 is randomlychanged. As described above, the position at which data is to berecorded can be obtained by pre-formatted address information,regardless of whether the data has already been recorded or not.Accordingly, the beginning position or the termination position ofrecording can be randomly changed with respect to the absolute positionon the optical disc medium 101 which is obtained by reproducing theaddress information. In this case, it is preferable that the end of therecord finish VFO portion 2101 is positioned rearward with respect tothe start of the record start VFO portion 2102.

As described above, the beginning position and the termination positionof additional data recording are set so that the relationship S : E isalways fulfilled. Therefore, at least a portion of the record finish VFOportion 2101 (the fourth synchronization code sequence already recordedon the optical disc medium 101 is overwritten by the record start VFOportion 2102 (the first synchronization code sequence of the VFO patternrecorded when additional data recording is performed.

As described above, in the first example of the present invention, adata block which is the minimum unit of recording and reproductionincludes a first frame area at the start and a frame area locatedsubsequent to the first frame area. The first frame area includes afirst synchronization area (PA) and a second synchronization area (VFO).The second frame area includes a third synchronization area (SY) and adata area (DATA) for recording data. Due to such a structure, thebeginning/termination of data recording (linking) can be performed inthe second synchronization area (VFO) in the first frame area (linkingframe area). Various fluctuation factors in the data recording can beabsorbed within the second synchronization area VFO, and thus stabledata recording and reproduction can always be provided. Overhead is keptsmall at slightly more than one frame per data block.

According to the present invention, it is not necessary to precisely setthe positioning accuracy to less than one channel bit. Accordingly, adriving apparatus can be designed with a simple structure, thus reducingthe production cost of the driving apparatus.

FIG. 7A shows an exemplary recording pattern of a beginning position ofa usual frame area (i.e., the second frame area 202) and FIG. 7B showsan exemplary recording pattern of a beginning position of a linkingframe area (i.e., the first frame area 201) both in the first example ofthe present invention. The examples shown in FIGS. 7A and 7B areobtained when a run length limited code having parameters of d=1, k=9,and n/m=1.5 is used for modulation of the data area.

In FIG. 7A, the beginning position of the usual frame area refers to thestart of the second frame area 202 (FIG. 2) in conformity of the dataformat of the first example of the present invention. At the start ofthe second frame area 202, the third synchronization area SY is providedhaving a length of two bytes (i.e., 24 channel bits). The data area DATAis provided from the third byte. In the SY pattern of the thirdsynchronization area SY, the underlined partial pattern“10000000000001001” corresponds to the pattern of (Tmax+3)·(Tmin+1) in arun length limited code having parameters of d=1 and k=9. “YYYYYY” atthe start of the SY pattern (left of FIG. 7A) is preferably determinedso as to fulfill the run length limitation of d=1 and k=9 inconsideration of the connection with the immediately preceding data areaDATA.

In FIG. 7B, the beginning position of the linking frame area refers tothe start of the first frame area 201 in conformity of the data formatof the first example of the present invention. At the start of the firstframe area 201, the first synchronization area PA is provided having alength of two bytes (i.e., 24 channel bits). The second synchronizationarea VFO is provided from the third byte. The underlined partial pattern“10000000000001000001” in the first synchronization area PA and thesecond synchronization area VFO corresponds to the pattern of (Tmax+3)(Tmin+4) in a run length limited code having parameters of d=1 and k=9.The unique pattern of the linking frame area, i.e., the pattern of((Tmax+3) (Tmin+4)) and the unique pattern of the usual frame area,i.e., the pattern of ((Tmax+3),(Tmin+1)) have the relationship that thelength from the beginning position to the beginning position of (Tmax+3)is the same (8 channel bits) and the termination position of (Tmax+3) isthe same.

In FIG. 7B, “YYYYYY” at the start is preferably determined so as tofulfill the run length limitation of d=1 and k=9 in consideration of theconnection with the immediately preceding data area DATA. “YYYYYY” inFIG. 7B can be exactly the same as the “YYYYYY” in the SY pattern inFIG. 7A. Even in this case, the code distance between the PA pattern andthe SY pattern can be still 3 since the pattern immediately after(Tmax+3) in the SY pattern is (Tmin+1) whereas the pattern immediatelyafter (Tmax+3) in the PA pattern is (Tmin+4).

Accordingly, even when, for example, the SY pattern and the PA patterneach have a length of 2 bytes and thus many types patterns cannot beformed when (Tmax+3) is included in the 2-byte length, the number oftypes of patterns which can be distinguished by the length of thepattern immediately after (Tmax+3) can be increased. Thus, the degree offreedom of use of patterns is increased.

When the degree of freedom of use of patterns is increased, it is alsopossible to increase the number of types of patterns usable as an SYpattern or a PA pattern while maintaining the code distance at 2 ormore, or conversely to increase the code distance to 3 or more whilemaintaining the number of types of patterns usable as an SY pattern or aPA pattern.

The byte length of the first frame area 201 and the second frame area202, and the number of the second frame areas 202 in each data block 103in this example will be described.

It is preferable that the byte length of the first frame area 201 andthe byte length of the second frame area 202 are preferablysubstantially identical to each other, or the byte length of one of theareas is substantially integral times the byte length of the other. Bymaking the byte length of one of the first frame area 201 and the secondframe area 202 substantially integral times the byte length of theother, it becomes possible to use the same circuits (timing generationcircuit and the like) of a recording/reproduction apparatus, forexample, for data generation in both of the frame areas when recordingdata and for frame interpolation in both of the frame areas whenreproducing data. Thus, the scale of the recording/reproductionapparatus can be reduced, and thus the cost can be reduced. In the firstexample of the present invention, the first frame area 201 and thesecond frame area 202 both have a length of 93 bytes. Alternatively, thebyte length of the first frame area 201 can be about an integer timesthe byte length of the second frame area 202.

In the case where the first frame area 201 has a length of 93 bytes, thepattern shown in FIG. 3 is located in the first synchronization area PA,and the pattern shown in FIG. 4 is located in the second synchronizationarea VFO, the first synchronization area PA has a length of 2 bytes andthe second synchronization area VFO has a length of 91 bytes. In thiscase, the pattern in the second synchronization area VFO includes 4Trecording marks or spaces repeated 182 times.

In the first example of the present invention, the number of the secondframe areas 202 in each data block 103 is 208. This number determinesthe frequency at which the first frame area 201 is inserted and the datasize of the data block 103. When this number is large, the overhead(redundant portion of the format) caused by the first frame area 201which does not have the data area DATA is small and thus the effect ofincreasing the storage capacity of the optical disc medium 101 isobtained. However, such a large number is disadvantageous when handlingsmall size data since the data size of the data block 103 is increased.

As shown in FIG. 2, an ECC block includes 4 continuous data blocks 103.In this case, the number of the second frame areas 202 per ECC block is208×4=832. The ECC block is defined as a coding unit of an errorcorrection code. For example, in the case where a known product code isformed using a known Reed-Solomon code two-dimensionally as an errorcorrection code, the ECC block is the unit of the product code. Wherethe third synchronization area SY has a length of 2 bytes, the totalsize of all the data areas DATA per ECC block is 91×832=75712 bytes. Inthe first example of the present invention, 65536 bytes of the 75712bytes are used for user data, and the remaining bytes are allocated toredundant data such as an error correction, block identification ID andthe like.

By forming an ECC block forming an error correction code of an integernumber of data blocks, each of which is the minimum unit of a series ofdata recording, an effect of facilitating the management of therecording data in a driving apparatus (recording apparatus orreproduction apparatus) is provided. In the first example of the presentinvention, 1 ECC block=4 data blocks, but the present invention is notlimited to this. A similar effect is provided even when the number ofdata blocks included in one ECC block is changed. For example, 1 ECCblock can include one data block. However, in the first example, thenumber of the data blocks included in one ECC block inevitably has anupper limit since the leading frame area of each data block is the firstframe area 201 (i.e., redundant data) which does not include a data areaDATA. The number of data blocks included in one ECC block is preferablydetermined to be a value suitable to the use of the optical discapparatus 101, the performance of the driving apparatus and the like inconsideration of the error correction capability of the drivingapparatus and the overhead.

The pattern recorded in the third synchronization area SY need not beidentical regardless of the second frame area 202. For example, thesecond frame area 202 subsequent to the first frame area 201 in eachdata block 103 can have a specific pattern which is different from thepattern recorded in the other second frame area 202. In this manner, theabove-mentioned specific pattern can be identified by the drivingapparatus. Therefore, the first data area DATA in each data block 103can be detected at a higher accuracy, which raises the reliability ofthe driving apparatus. In a second example described below, the SYpattern recorded at the start of one of a plurality of second frameareas 202 is different from the SY pattern recorded at the start of theother second frame areas 202.

In the first example, the first frame area (first area and third area)includes a first synchronization area PA and a second synchronizationarea VFO, but can include other synchronization code sequences or databit streams.

EXAMPLE 2

FIG. 8 shows a top view of a recordable optical disc medium (recordingmedium) 3101 according to a second example of the present invention. Asshown in FIG. 8, on a recording surface of the optical disc medium 3101,a recording track 3102 (recording area) is formed in a spiral manner.The recording track 3102 is divided into data blocks 301. In otherwords, on the recording surface of the optical disc medium 3101, thedata blocks 301 are continuously arranged in a circumferential directionto form the information track 3102.

FIG. 9 shows an example of a data format of the optical disc medium 3101in the second example of the present invention. In FIG. 9, identicalelements as those described above with reference to FIG. 2 bearidentical reference numeral therewith and will not be described indetail. In FIG. 9, an area shown in the right is rearward to an areashown in the left.

As shown in FIG. 9, each data block 301 includes a first frame area 201and 8 sectors 3103. Four data blocks 301 form one ECC block 302.Accordingly, one ECC block includes 32 sectors.

A plurality of second frame areas included in each data block 301 aregrouped into a plurality of sectors 3103 each including 26 second frameareas.

Each sector 3103 (fourth area) includes 26 second frame areas. Eachframe area has a length of 93 bytes. The frame area positioned at thestart of the sector 3103 is represented by reference numeral F0, and theremaining 25 frame areas are represented by reference numerals F1, F2, .. . F24 and F25.

The frame area F0 includes a synchronization area SY0 (thirdsynchronization area) at the start thereof and then a data area DATAsubsequent thereto. The frame areas F1 through F25 each include asynchronization area SY (the third synchronization area) at the startthereof and then a data area DATA subsequent thereto. Thesynchronization area SY0 and the synchronization area SY both have alength of 2 bytes. Accordingly, the length of each of all the data areasDATA in the frame area F0 and the frame areas F1 through F25 is 91bytes.

The total number of bytes of all the data areas DATA in each sector 3103is 91×26=2366 bytes. User data to be recorded in each sector has alength of 2048 bytes, and redundant data such as address information foridentifying the recording position of the data, a parity code used fordetecting or correcting an error and the like has a length of 318 bytes.The total of the user data and the redundant data is 2366 bytes.

The data bit stream to be recorded in the data area DATA is not recordedas binary data itself, but is transformed by a modulation systemmatching the characteristics of a recording and reproduction signal ofthe optical disc medium before being recorded. It is assumed here thatNRZI recording is performed using an 8/16 modulation system. The databit stream to be recorded in each data area DATA has a length of91×16=1456 channel bits, and includes recording marks or spaces having aminimum length Tmin of 3 bits and a maximum length Tmax of 11 bits.

The synchronization area SY0 is provided for identifying the start ofthe frame area F0, and preferably has a pattern recorded which does notoccur in at least a data bit stream to be recorded in the data areaDATA. By recording a pattern, in the synchronization area SY0, whichdoes not occur in the data area DATA, the synchronization area SY0 canbe easily distinguished from the data area DATA when the data bit streamis read.

Each synchronization area SY is provided for identifying the start ofthe respective second frame of the second frame areas F1 through F25.Each synchronization area SY preferably has a pattern recorded whichdoes not occur in at least a data bit stream to be recorded in the dataarea DATA, like the synchronization area SY0 in the frame area F0. Byrecording a pattern, in the synchronization area SY, which does notoccur in the data area DATA, the synchronization area SY can be easilydistinguished from the data area DATA when the data bit stream is read.Hereinafter, the pattern recorded in the synchronization area SY or thesynchronization area SY0 will also be referred to as a “synchronizationcode sequence”.

FIG. 10 shows an example of synchronization code sequences located atthe start of each of the 26 frame areas included in the sector 3103(FIG. 9). The synchronization code sequences are classified into twotypes, the SY0 pattern and the SY pattern. The SY pattern is located inthe second through the 26th frame areas.

FIG. 11 shows an example of a pattern preferably used as asynchronization code sequence in the second example of the presentinvention. The pattern shown in FIG. 11 includes a recording mark orspace having a length of 14 channel bits (14T), which is a (Tmax+3)channel bit length. In the second example, as described above, themaximum mark/space length Tmax of a data bit stream to be recorded inthe data area DATA is 11 channel bits (11T), which is different, by 3bits, from 14T included in the synchronization code sequence. Even whena 1 channel bit edge shift occurs due to the influence of noisegenerated during reproduction, and as a result, the 14T mark (or the 14Tspace) in the synchronization code sequence shortens to 13 channel bitsand the 11T mark (or the 11T space) in the data area DATA lengthens to12 channel bits, there is still a 1 channel bit difference between themark (or space) in the synchronization code sequence and the mark (orspace) in the data area DATA. Thus, against an edge shift of about onebit, a sufficient error margin is provided for preventing the 11Tpattern in the data area DATA from being incorrectly detected as thepattern in the synchronization code sequence.

In order to distinguish the SY0 pattern and the SY pattern from eachother, it is preferable to provide a code distance therebetween of 2 ormore. Herein, the code distance refers to the number of bits which aredifferent between the two data bit streams. In the case of the NRZrecording, the code distance is given by the data bit stream in the NRZrepresentation. In the case of the NRZI recording, the code distance isgiven by the data bit stream in the NRZI representation. When the codedistance between the SY0 pattern and the SY pattern is equal to orgreater than 2, one pattern is not incorrectly identified as the otherpattern even when a 1 bit shift error occurs in reading one of thepatterns.

When the code distance is equal to or greater than 3, the identificationcapability is further improved. For example, with the code distance of2, when the SY0 pattern and the SY pattern shift by one bit in thedirection of approaching each other, the two patterns become identicaland cannot be distinguished from each other. With the code distanceequal to or greater than 3, by contrast, when the SY0 pattern and the SYpattern shift by one bit in the direction of approaching each other,there is still a difference equal to or greater than one bit, and thetwo patterns can be distinguished from each other. Therefore, the SY0pattern and the SY pattern can always be distinguished from each otherwhile keeping the tolerance of a 1 bit error. A plurality of types of SYpatterns can be used as long as the code distance between the SY0pattern and each of the SY patterns is equal to or greater than 2.

FIG. 12 shows a specific example of the SY0 pattern and the SY patternin the second example of the present invention. The SY0 pattern and theSY pattern both have a length of 2 bytes (i.e., 32 channel bits) andboth include a common unique pattern of (14T+4T). One advantage ofmatching the length of the two patterns and causing the two patterns toinclude a common unique pattern is that a device for detecting thepatterns can be simplified since the device can include a common patterndetection system for the two patterns.

The unique pattern corresponds to the pattern of (Tmax+3)·(Tmin+1) inthe 8/16 modulation system. The detection capability of the patternitself is improved by locating a space (or mark) having (Tmin+1) bitsimmediately after a mark (or space) having (Tmax+3) bits. In otherwords, by using (14T+4T) as the detection pattern when the data in thedata block 3103 is read, the possibility of incorrect detection can bereduced compared to using only 14T as the detection pattern. By adding(15T+3T) or (13T+5T) to the detection pattern, not only (14T+4T), 14Tcan be avoided from being undetected even when an edge shift occurs atthe rear end of the 14T, and still the possibility of incorrectdetection can be kept as low as possible.

FIG. 12 shows four types of patterns usable as an SY0 pattern and fourtypes of patterns usable as an SY pattern (two types for State 1 andState 2 and two types for State 3 and State 4). Herein, States 1 through4 represent index information indicating which of a plurality oftransformation tables of the 8/16 modulation system is to be selected.The patterns for State 1 and State 2 have a feature that the zero run onthe MSB side (left in FIG. 12) is 2 or 3. The patterns for State 3 andState 4 have a feature that the zero run on the MSB side (left in FIG.12) is 0: i.e., the MSB starts with a “1” bit.

Now, how to make a selection from the four SY0 patterns will bedescribed. When the modulation result immediately before thesynchronization area SY0, i.e., the next state after the last data bytein the data area DATA in the frame area F25 is modulated, is 1 or 2,State 1 and State 2 are selected. Otherwise, State 3 and State 4 areselected. In this way, the zero run can be within a prescribed range(within the range of 2 to 10) at the connection point of the last byteof the frame area F25 and the SY0 pattern. Regarding the SY pattern, theselection is performed in a similar manner.

Next, how to select a first selection code sequence (shown in the lefthalf of FIG. 12) or a second selection code sequence (shown in the righthalf of FIG. 12) will be described. In the first selection codesequence, CDS (Codeword Digital Sum) is a positive value; and in thesecond selection code sequence, CDS is a negative value. Here, CDS is avalue obtained by summing up all the bits in the code sequence (pattern)which is obtained by NRZI transformation of the code sequence, assumingthat the MSB is 1. The summation is performed with the bit “1” being +1and the bit “0” being −1. Namely, a sum of the immediately preceding DSVvalue and the CDS of the code sequence is the DSV value after the codesequence is selected. Since the sign of the CDS of the first selectioncode sequence and that of the second selection code sequence areopposite to each other, selection of one of them allows the value of DSVcloser to zero. As a result, the value of DSV can be effectivelycontrolled.

The most noticeable feature of the patterns in FIG. 12 will bedescribed. The most noticeable feature is that the code distancesbetween the four types of patterns usable as the SY0 pattern and thefour types of patterns usable as the SY pattern are all equal to orgreater than 2 (in the NRZI representation).

For example, a code distance between the underlined pattern among thepatterns usable as the SY0 pattern, “10010001000001000000000000010001”and each of the four patterns usable as the SY patterns will be checked.The code distance between the above-mentioned underlined pattern and thepattern “00010000000001000000000000010001” in the NRZI representation is7. This code distance is found by comparing a pattern “11100001111110 .. . ” obtained by NRZI-transforming the former pattern beginning withbit “1” and a pattern “00011111111110 . . . ” obtained byNRZI-transforming the latter pattern beginning with bit “0”.

Similarly, the code distance between the above-mentioned underlinedpattern and the pattern “00100000001001000000000000010001” is 4, thecode distance between the above-mentioned underlined pattern and thepattern “10001000010001000000000000010001” is 3, and the code distancebetween the above-mentioned underlined pattern and the pattern“10001000000001000000000000010001” is 6. Thus, all the code distancesfulfill the condition of being equal to or greater than 2. By keepingall the code distances of the SY0 patterns and the SY patterns to beequal to or greater than 2, the possibility of incorrect identificationof the two patterns can be reduced even when an error such as a bitshift or the like occurs. By having only the leading frame area F0 ofthe sector 3103 distinguished from the other frame areas F1 through F25,the start of the sector 3103 can be easily detected. A pattern to berecorded in the synchronization area SY at the start of each of theframe areas F1 through F25 can be any of a plurality of patterns whichinclude a pattern having (Tmax+3) bits and a pattern having (Tmin+1)bits and fulfill the condition of the code distance from the SY0 patternbeing equal to or greater than 2.

FIG. 13 schematically shows different code distances between the typesof synchronization code sequences (patterns). FIG. 13 shows therelationship between the synchronization code sequence SY0 (SY0 pattern)and the synchronization code sequence SY (SY pattern). When the codedistance therebetween is only 1, occurrence of a 1 bit error while theSY0 pattern is read results in the SY0 pattern being read as identicalto the SY pattern. Therefore, when a 1 bit error occurs, the type of thepattern read cannot be determined even by complete matchingdetermination (determination technique by which the two patterns aredetermined to be identical to each other only when the entire patternscompletely match each other).

When the code distance between the SY0 pattern and the SY pattern is 2,occurrence of a 1 bit error in one of the patterns does not result inthe two patterns being identical to each other. Even when a 1 bit erroroccurs in both of the patterns, the type of the pattern read can bedetermined as long as complete matching determination is used.Accordingly, determination of types of synchronization code sequences ispossible with complete matching determination.

When the code distance between the SY0 pattern and the SY pattern is 3,even occurrence of a 1 bit error in both of the patterns still leavesthe code distance of 1. Accordingly, even when a determination techniquefor allowing a 1 bit error is used, the type of the pattern read can bedetermined. When complete matching determination is used, even a 2 biterror can be allowed.

From the above description, it is appreciated that using a code distancebetween types of synchronization code sequences equal to or greater than3, the reliability is higher compared to using a code distance of 2.

FIG. 14 shows an exemplary internal structure of the frame area F0. Inthe example shown in FIG. 9, the data area DATA is simply locatedimmediately after the synchronization area SY0. In the example shown inFIG. 14, by contrast, a data position identification area DataID and anerror correction area Parity for the data position identification areaare provided immediately after the synchronization area SY0. Due to sucha structure, the content of the data position identification area DataIDcan be read immediately after the SY0 pattern recorded in thesynchronization area SY0 is detected. The content of the data positionidentification area DataID can include, for example, a sector number. Inthis case, the position of the sector can be determined only by readingthe data position identification area DataID. Accordingly, the positionof the sector can be identified only by detecting the SY0 pattern, whichallows the reproduction apparatus to detect the sector easily andquickly.

FIG. 15 shows specific examples of the SY0 pattern, the SY pattern, andthe PA pattern in the second example of the present invention. The SY0pattern and the SY pattern are exactly the same as those described abovewith reference to FIG. 12 and will not be described in detail.

The PA pattern is determined in a manner similar to the manner used forthe SY0 pattern and the SY pattern described above with reference toFIG. 12. The PA pattern has a length of 2 bytes (i.e., 32 channel bits).For conformity with the 8/16 modulation system, state control (selectionof the patterns for State 1 and State 2 or the patterns for State 3 andState 4) is possible and also the DSV control (selection of thepatterns, the signs of CDS of which are opposite to each other, i.e.,positive or and negative) is possible. The DSV control suppresses the DCcomponents of the post-modulation data bit stream.

The SY0 pattern, the SY pattern and the PA pattern all include a commonunique pattern of (14T+4T). One advantage of the three patterns havingthe same bit number and including a common unique pattern is that adevice for detecting the patterns can be simplified since the device caninclude a common pattern detection system for the three patterns.

The most noticeable feature of the patterns in FIG. 15 is that the codedistances between the four types of patterns usable as the SY0 pattern,the four types of patterns usable as the SY pattern and the four typesof patterns usable as the PA pattern are all equal to or greater than 2(in the NRZI representation).

For example, a code distance between the underlined pattern among thepatterns usable as the PA pattern, “00000010010001000000000000010001”,and each of the four patterns usable as the SY0 patterns and each of thefour patterns usable as the SY patterns will be checked. The codedistance between the above-mentioned underlined pattern and the SY0pattern “0010010000100100000000000001001” in the NRZI representation is4. This code distance is found by comparing a pattern “11111100011110 .. . ” obtained by NRZI-transforming the former pattern beginning withbit “1” and a pattern “00111000001110 . . . ” obtained byNRZI-transforming the latter pattern beginning with bit “0”.

Similarly, the code distance between the above-mentioned underlinedpattern and the SY0 pattern “00010000100001000000000000010001” is 4, thecode distance between the above-mentioned underlined pattern and the SY0pattern “10010001000001000000000000010001” is 5, and the code distancebetween the above-mentioned underlined pattern and the SY0 pattern“10000000010001000000000000010001” is 6. Thus, all the code distancesfulfill the condition of being equal to or greater than 2. The codedistance between the above-mentioned underlined pattern and the SYpattern “00010000000001000000000000010001” is 6, the code distancebetween the above-mentioned underlined pattern and the SY pattern“00100000001001000000000000010001” is 5, the code distance between theabove-mentioned underlined pattern and the SY pattern“10001000010001000000000000010001” is 3, and the code distance betweenthe above-mentioned underlined pattern and the SY pattern“10001000000001000000000000010001” is 7. Thus, all the code distancesfulfill the condition of being equal to or greater than 2.

In the above, the specific examples of the SY0 pattern, the SY pattern,and the PA pattern when the post-modulation data bit stream isrun-length-limited to Tmin=3 and Tmax=11 are described. Hereinafter,with reference to FIG. 16, specific examples of the SY0 pattern, the SYpattern, and the PA pattern when Tmin=2 and Tmax=8 will be described.The patterns described below are especially preferable when, forexample, the data area DATA is transformed using a so-called (1-7)modulation system, i.e., a run length limited code system havingparameters of d=1, k=7, m=2 and n=3.

FIG. 16 shows, as described above, the specific examples of the SY0pattern, the SY pattern, and the PA pattern preferable in the secondexample of the present invention. The patterns shown in FIG. 16 all havea feature of including a pattern “100000000001001” in the NRZrepresentation as underlined. The common pattern corresponds to thepattern of (Tmax+3) (Tmin+1) of the (1-7) modulation system. Anadvantage of providing such a common unique pattern is as describedabove in the first example.

In the example shown in FIG. 16, four types of patterns usable as an SY0pattern, four types of patterns usable as an SY pattern and four typesof patterns usable as a PA pattern are provided (two types for the casewhere the LSB of the immediately preceding code word is “0”, i.e., inthe case where the inversion does not occur at the LSB by the NRZIrepresentation; and two types for the case where the LSB of theimmediately preceding code word is “1”, i.e., in the case where theinversion occurs at the LSB by the NRZI representation). Theclassification based on the LSB of the immediately preceding code wordcorresponds to the Tmin of 2 in the (1-7) modulation system. In otherwords, by performing the above-described selection based on whether thezero run on the LSB side is 0, or equal to or greater than 1, when theimmediately preceding data is modulated, the run length limitation canbe fulfilled at the connection portion.

The first selection code sequence (shown in the left half of FIG. 16)has a CDS of a positive value, and the second selection code sequence(shown in the right half of FIG. 16) has a CDS of a negative value.Thus, the DSV value can be effectively controlled as described abovewith reference to FIG. 15.

The most noticeable feature of the patterns in FIG. 16 is that the codedistances between the four types of patterns usable as the SY0 pattern,the four types of patterns usable as the SY pattern and the four typesof patterns usable as the PA pattern are all equal to or greater than 2(in the NRZI representation).

For example, a code distance between the upper left pattern among thepatterns usable as the SY0 pattern, “010000000100000000001001”, and eachof the four patterns usable as the SY patterns and each of the fourpatterns usable as the PA patterns will be checked. The code distancebetween the above-mentioned underlined pattern and the SY pattern“010001010100000000001001” in the NRZI representation is 2. This codedistance is found by comparing a pattern “1000000001 . . . ” obtained byNRZI-transforming the former pattern beginning with bit “1” and apattern “1000011001 . . . ” obtained by NRZI-transforming the latterpattern beginning with bit “1”.

Similarly, the code distance between the above-mentioned underlinedpattern and the SY pattern “010010000100000000001001” is 4, the codedistance between the above-mentioned underlined pattern and the SYpattern “101010000100000000001001” is 3, and the code distance betweenthe above-mentioned underlined pattern and the SY pattern“100010000100000000001001” is 3. Thus, all the code distances fulfillthe condition of being equal to or greater than 2. The code distancebetween the above-mentioned underlined pattern and the PA pattern“010101000100000000001001” is 2, the code distance between theabove-mentioned underlined pattern and the PA pattern“010101010100000000001001” is 5, the code distance between theabove-mentioned underlined pattern and the PA pattern“10001000100000000001001” is 3, and the code distance between theabove-mentioned underlined pattern and the PA pattern“101010100100000000001001” is 3. Thus, all the code distances fulfillthe condition of being equal to or greater than 2.

By keeping all the code distances with relation to the SY0 patterns, theSY patterns and the PA patterns to be equal to or greater than 2, thepossibility of incorrect identification of the three patterns can bereduced even when an error such as a bit shift or the like occurs. Thus,the leading frame area F0 of the sector 3103 can be distinguished fromthe other frame areas F1 through F25, which facilitates detection of thestart of the sector 3103.

The first frame area 201 corresponding to the linking frame area can bedistinguished from the other frame areas with certainty, whichfacilitates detection of the linking position. By detecting the linkingposition, the discontinuity of data caused by linking can beappropriately processed with ease. The process performed by a recordingapparatus during the additional data recording and the process performedin the linking frame area by a reproduction apparatus will be describedbelow in sixth and seventh examples.

FIG. 17 shows another example of synchronization code sequences locatedat the start of each of the 26 frame areas included in the sector 3103(FIG. 9). In the example shown in FIG. 17, the SY0 pattern is located inthe leading frame area of the sector 3103. In the subsequent frameareas, {SY1•SY1•SY2•SY1•SY1•SY2•SY1 . . . SY1•SY2•SY1} are locatedsequentially from the immediately subsequent frame area. In thisexample, an SY2 pattern is located at a frequency of one in threecontinuous frame areas, except for the leading frame area.

FIGS. 18A through 18D show examples in which synchronization codesequences to be recorded in the second frame areas included in onesector are arranged in the order in which the synchronization codesequences are recorded on an optical disc medium. FIG. 18A correspondsto the arrangement of the synchronization code sequences described abovewith reference to FIG. 10. In the example shown in FIG. 18A, only thesynchronization code sequence (SY0 pattern) located in the leading framearea is of a different type from that of the synchronization codesequences (SY pattern) located in the other frame areas. Therefore, whenone frame slip occurs at a position in the sector due to a defect of arecording surface of the optical disc medium or the like, it isdifficult to determine the position of the frame area currently readuntil the next SY0 pattern is detected.

In the arrangement of FIG. 18B which uses three types of patterns ofSY0, SY1 and SY2, by checking an arrangement of a minimum of threecontinuous frame areas (for example, {SY1•SY2•SY1}), it can bedetermined whether one forward frame slip has occurred or one rearwardframe slip has occurred. Since the SY0 pattern is expected to bedetected immediately after the arrangement of {SY1•SY2•SY1}, the startof the sector can be detected more reliably than in the case where onlythe SY0 pattern is detected.

An effective arrangement of the three types of patterns of SY0, SY1 andSY2 is not limited to the above-described arrangement. The arrangementimmediately after the SY0 pattern can be {SY1•SY2•SY1•SY1•SY2 . . . } asshown in FIG. 18C, or {SY2•SY1•SY1•SY2•SY1 . . . }. A similar effect asthat described above can be provided. Alternatively, one cycle caninclude equal to or greater than four patterns. FIG. 18D shows one suchexample, i.e., {(SY1•SY1•SY1•SY2•SY1•SY1•SY1•SY2 . . . }.

The above-described manner of arrangement of synchronization codesequences in the second frame areas can be generalized as follows. TheSY2 pattern is located at the start of the Mth frame area of the sectorand the SY1 pattern is located at the start of each of the other frameareas. Here, “M” fulfills M=J×K+L, where M is a natural number equal toor less than N (N is the total number of second frame areas included inone sector and is an integer equal to or greater than 3), J and L areconstants (J is an integer equal to or greater than 2 and L is a naturalnumber equal to or less than J), and K is an integer equal to or greaterthan 0. When the patterns are located in this manner, by checking anarrangement of a minimum of J continuous frame areas, it can bedetermined whether up to (J-1) forward frame slips have occurred or upto (J-1) rearward frame slips have occurred.

The examples shown in FIGS. 18B and 18C correspond to the case whereN=26, J=3 and K=0 through 8.

When three types of patterns are repeated at a cycle of four patterns(four frame areas), up to two frame slips can be determined by checkingan arrangement of a minimum of four continuous frame areas. As thenumber of frame areas included in one cycle is increased to 5, 6, . . ., the number of frame slips which can be detected is increased. However,as the number of frame areas included in one cycle is increased, thenumber of continuous frame areas of an arrangement required to bechecked is also increased. Thus, it takes a longer time period todetermine the frame slip. In the case where the number of bits of anerror is excessive, it is difficult to check the arrangement and mayundesirably spoil the reliability of the reproduction apparatus.Accordingly, the cycle of the frame areas is determined to be optimum inaccordance with the maximum number of frame slips which should bedetected or other elements required by the reproduction apparatus.

FIGS. 19A through 19C show other examples in which synchronization codesequences to be recorded in the second frame areas included in onesector are arranged in the order in which the synchronization codesequences are recorded on an optical disc medium. FIG. 19A is identicalwith FIG. 18A but is provided for the sake of reference. In FIG. 19B,only the synchronization code sequence (SY2 pattern) located in thefinal frame area is of a different type from that of the synchronizationcode sequences (SY1 pattern) located in the other frame areas. In thiscase, the reliability of detecting the start of the sector can beimproved by detecting an arrangement of three continuous patterns{SY1•SY2•SY1} as compared to the case where only the SY0 pattern isdetected. Alternatively, as shown in FIG. 19C, the differentsynchronization code sequence (SY2 pattern) can be located in the finalplurality of frame areas of the sector instead of final one frame areaof the sector.

FIG. 20 shows still another example in which synchronization codesequences to be recorded in the second frame areas included in onesector are arranged in the order in which the synchronization codesequences are recorded on an optical disc medium. In the example shownin FIG. 20, the synchronization code sequence (SY2 pattern) located in amiddle frame area of the sector is of a different type from that of thesynchronization code sequences (SY1 pattern) located in the other frameareas. When, for example, the SY2 pattern is located in the 14th framearea of the sector, the pattern (SY2 pattern) of a different type fromthat of the other patterns (SY1 pattern) is recorded every ½ sector (13frame areas). Thus, the start of the sector can be detected more quicklyand a higher reliability. In the case where two types of patterns of SY0and SY are used, the SY0 pattern needs to be detected for severalcontinuous sectors in order to detect the start of the sectors with ahigher reliability. In the case where the three types of patterns ofSY0, SY1 and SY2 are arranged as shown in FIG. 20, the start of thesectors can be detected with a higher reliability only by detecting thearrangement of {SY0•SY2} every 13 frame areas.

As described above, by appropriately arranging three types ofsynchronization code sequences in a plurality of frame areas included inone sector, the reliability of detecting the start of the sector can beimproved as compared to the case where two types of synchronization codesequences are used.

When three types of synchronization code sequences are used, a higherreliability is obtained by setting all the code distances to equal to orgreater than 2 (or equal to or greater than 3). As long as the SY0pattern is away from the other two types of patterns by a code distanceequal to or greater than 2 (or 3), the effect of improving thereliability of detecting the start of the sector is obtained.

Hereinafter, examples of arrangement in the case where four types ofsynchronization code sequences are used will be described.

FIG. 21 shows still another example of synchronization code sequenceslocated at the start of each of the 26 frame areas included in thesector 3103 (FIG. 9). In the example shown in FIG. 21, one sectorincludes 26 frame areas. Four types of synchronization code sequencesSY0, SY1, SY2 and SY3 are located in the 26 frame areas. In the firstframe area, the SY0 pattern is located. In the subsequent frame areas,SY1•SY2•SY3•SY1•SY2•SY3 . . . SY1•SY2•SY3•SY1} are located sequentiallyfrom the second frame area. In this example, the SY2 pattern and the SY3pattern are each located at a frequency of one in three continuous frameareas, except for the leading frame area.

FIGS. 22A through 22C show examples in which synchronization codesequences to be recorded in the second frame areas included in onesector are arranged in the order in which the synchronization codesequences are recorded on an optical disc medium, when four types ofpatterns SY0, SY1, SY2 and SY3 are used. FIG. 22A corresponds to thearrangement of the synchronization code sequences described above withreference to FIG. 21. In the example shown in FIG. 22A, even when oneframe slip occurs at a position in the sector, it can be detectedwhether a forward slip has occurred or a rearward slip has occurred bychecking an arrangement of a minimum of three continuous frame areas,for example, {SY1•SY2•SY3}. Since the SY0 pattern is expected to bedetected immediately after the arrangement of {SY1•SY2•SY1}, the startof the sector can be detected more reliably than in the case where onlythe SY0 pattern is detected.

Alternatively, as shown in FIG. 22B, in order to guarantee the detectionof the SY0 pattern of the next sector, only the synchronization codesequence (SY3 pattern) in the final frame area of the sector can be of adifferent type from that of the synchronization code sequences locatedin the other frame areas. In this case, by, for example, detecting anarrangement of {SY2•SY3•SY0}, the reliability of detecting the start ofthe sector can be improved as compared to the case where only the SY0pattern is detected. Regarding the other frame areas, even a frame slipat a position in the sector can be detected when repeating thearrangement of {SY1•SY1•SY2} as described above with reference to FIGS.18B through 18D.

Still alternatively, as shown in FIG. 22C, only the synchronization codesequence (SY3 pattern) in a middle frame area of the sector can be of adifferent type from that of the synchronization code sequences locatedin the other frame areas. In the other frame areas, the arrangement of{SY1•SY1•SY2} can be repeated. In this case, the reliability ofdetecting the start of the sector can be improved by checking thearrangement including the SY3 pattern every ½ sector. In addition, thereliability of detecting a frame slip can be improved.

As described above, by appropriately arranging four types ofsynchronization code sequences in a plurality of frame areas included inone sector, the frame synchronization/sector synchronization performancecan be improved in addition to the effect provided by using three typesof synchronization code sequences.

When four types of synchronization code sequences are used, a higherreliability is obtained by setting all the code distances to equal to orgreater than 2 (or equal to or greater than 3). As long as the SY0pattern is away from the other three types of patterns by a codedistance equal to or greater than 2 (or 3), the effect of improving thereliability of detection of the start of the sector is obtained.

As described above, in the optical disc medium 3101 according to thesecond example of the present invention, a first data unit (sector)includes a leading frame area (F0) and at least one frame area (F1through F25) located subsequent to the leading frame area (F0). Theleading frame area (F0) includes an area in which the SY0 pattern is tobe recorded and a data area (DATA) in which user data is to be recorded.Each of the at least one frame area (F1 through F25) includes an area inwhich the SY pattern is to be recorded and a data area (DATA) in whichuser data is to be recorded. The SY0 pattern and the SY pattern are allidentical in length and are set to have a code distance therebetweenwhich is equal to or greater than 2.

More specifically, the SY pattern (second synchronization code sequence)located in the leading frame area F0, among the 26 (a prescribed number)frame areas (F0 through F25), is away from the second synchronizationcode sequence located in each of the other frame areas (F1 through F25)by a code distance equal to or greater than 2.

Due to such a structure, the SY0 pattern is easily detected during datareproduction, and thus the start of each first data unit (sector) can bedetected quickly and with ease.

In the case where the code distance between the SY0 pattern and the SYpattern is equal to or greater than 3, the possibility of incorrectlydetecting the SY0 pattern as the SY pattern or vice versa is furtherreduced as compared to the case where the code distance is 2. The SY0pattern and the SY1 pattern can be distinguished from each other whilestill allowing for a 1 bit error. Accordingly, the stability of framesynchronization/sector synchronization and the reliability of detectingthe start of the first data unit (sector) can be further improved. Thus,the reliability of the reproduction apparatus can be raised.

By locating at least two types of synchronization code sequences (SY1and SY2, or SY1, SY2 and SY3) in the at least one frame area subsequentto the leading frame area, information on an arrangement ofsynchronization code sequences in continuous frame areas among the frameareas F1 through F25 can be obtained. Such information can be used toexpect the occurrence of the SY0 pattern in the next first data unit(sector) or detect and correct a frame slip caused due to an unlockingof the PLL section.

It is preferable to set code distances between the SY0 pattern in theleading frame area of the first data unit (sector) and the othersynchronization code sequences (SY1 and SY2, or SY1, SY2 and SY3) toequal to or greater than 2 (or 3). It is more preferable to set the codedistances between all the different types of synchronization codesequences to equal to or greater than 2 (or 3). In this manner, thereliability of detecting the start of a sector, and the reliability offrame synchronization caused by a malfunction such as unlocking of thePLL section or the like, can be further improved.

A prescribed number of first data units (sectors) form a second dataunit (data block). The first frame area 201 is located in every seconddata unit (data block). A PA pattern is located at the start of thefirst frame area 201. The SY0 pattern and the SY1 patterns are allidentical in bit length and are located to be away from each other by acode distance equal to or greater than 2. Due to such a structure, thePA pattern can be easily detected during data reproduction, and thestart of each second data unit (data block) can be detected quickly andwith ease. The beginning position and the termination position of aseries of information recording (linking) are set in the first framearea 201 (linking frame area). Therefore, the reliability of linking(additional recording) can be improved, and data reproduction ofinformation which is recorded in and in the vicinity of a linkingposition can be performed stably and at a high speed.

In the second example, the first frame area (first area and third area)includes a first synchronization area PA and a second synchronizationarea VF0, but can include other synchronization code sequences or databit streams. In the preferable examples described above, thesynchronization pattern PA to be recorded in the first frame area, thesynchronization pattern SY0 to be recorded in the second frame areawhich is positioned at the start of each sector, and the synchronizationpattern SY to be recorded in the second frame areas other than thesecond frame area which is positioned at the start of each sector areset to have an equal length and also to have a code distance equal to orgreater than 2 therebetween. The present invention is not limited tothis.

EXAMPLE 3

FIG. 23 shows a top view of a recordable optical disc medium 401according to a third example of the present invention. On a recordingsurface of the optical disc medium 401, a recording track 402 is formedin a spiral manner. The recording track 402 is divided into data blocks403. In other words, on the recording surface of the optical disc medium401, the data blocks 403 are continuously arranged in a circumferentialdirection to form the information track 402.

FIG. 24 shows a data format of the data blocks 403 of the optical discmedium 401 (FIG. 23) according to the third example of the presentinvention. As shown in FIG. 24, a first frame area 501 is located at thestart of each data block 403, and a plurality of second frame areas 502are located subsequent to the first frame area 501. The first frame area501 and the plurality of second frame areas 502 form one data block 403.In FIG. 24, an area shown in the right is rearward to an area shown inthe left.

The first frame area 501 includes a first synchronization area PA at thestart thereof, a second synchronization area VF0 subsequent thereto, andthen a fourth synchronization area PS at the end thereof. Each of thesecond frame areas 502 includes a third synchronization area SY at thestart thereof and a data area DATA subsequent thereto.

In the third example of the present invention, the first synchronizationarea PA, the second synchronization area VF0, the third synchronizationarea SY and the data area DATA have the same roles of those in the firstexample, and will not be described in detail. The third example isdifferent from the first example in that the fourth synchronization areaPS is provided at the end of the first frame area 501.

The fourth synchronization area PS has a role of assisting thereproduction apparatus to detect the start of the second frame area 502without fail when reading each data block 403 (especially when reading adata block 403 a corresponding to the start of the data additionallyrecorded). Data is recorded in the data block 403 a as follows. In afirst synchronization area PAa and a first portion of a secondsynchronization area VFOa in a first frame area 501 a (the Eth bytecounting from the start of the first synchronization area PAa), the datais recorded simultaneously with a data block 403 immediately precedingthe data block 403 a. Namely, the PA pattern and the record finish VFOportion 2101 are recorded in the first frame area 501 a. The additionalrecording (linking) is performed in the data block 403 a, from theposition at which the previous recording is terminated (from the 5th(S≦E) byte counting from the start of the first synchronization areaPAa). Namely, the record start VFO portion 2102 and the PS pattern arerecorded in the first frame area 501 a (third area). The third areaincludes an area in which the record start VFO portion 2102 is to berecorded and the fourth synchronization area PS in which the fifthsynchronization code sequence (PS pattern) is to be recorded.

In FIG. 24, the second frame area immediately subsequent to the firstframe area 501 a is represented by reference numeral 502 a. The secondframe area 502 a and the other second frame area 502 have a similarstructure to that of the second frame area 202 described above withreference to FIG. 2. In the following description, the thirdsynchronization area SY included in the second frame area 502 a will bespecifically represented by “SYa”.

As described above in the Prior Art section, a reproduction apparatusinvolves various error factors such as rotation jitter of a disc motorfor rotating an optical disc medium, a frequency of a recording channelclock and the like. Such error factors cause discontinuity at thebeginning position of additional data recording, which is in the secondsynchronization area VFOa. Therefore, the length of the first frame area501 a changes by an error (discontinuity), as compared to the length ofthe first frame area 501 of each of the other data blocks 403. When thisoccurs, it is difficult to correctly detect the third synchronizationarea SYa located at the start of the second frame area 502 a, eventhough level-slicing and locking of the clock frequency/phase by the PLLsection are performed with certainty when the reproduction apparatusreads data using the second synchronization area VFO. When the thirdsynchronization area SYa is not correctly detected, a data area DATAasubsequent to the third synchronization area SYa cannot be correctlymodulated. As a result, a reading error occurs.

In the third example of the present invention, the fourthsynchronization area PS is added in order to detect the start of thesecond frame area 501 a with certainty. As long as the fourthsynchronization area PS is detected, the data area DATAa can becorrectly modulated even when the third synchronization area SYa is notcorrectly detected. Thus, a resistance to error can be increased.

In the third example of the present invention, mark length recording isperformed using a run length limited code having parameters of d=2,k=10, m=8, n=16, and r=1 is used for modulation. Namely, the data bitstream to be recorded in the data area DATA includes recording marks orspaces having a Tmin of 3 bits and a Tmax of 11 bits.

FIG. 25 shows an example of a pattern to be recorded in the fourthsynchronization area PS (PS pattern), the example being especiallypreferable in the third example of the present invention. The patternshown in FIG. 25 is, in the NRZ representation, {0000 0100 0100 10000010 0001 0010 0000 1000 0010 0001 0000}. The pattern has 48 channelbits in total. The pattern has the features of: (i) strong autocorrelation; (ii) DSV=0; and (iii) a partial pattern obtained bydividing the pattern by 4 bits is one of the five types of 0000, 1000,0100, 0010 or 0001. When a run length limited code having the parametersof d=2, k=10, m=8, n=16 and r=1 is used for modulation of the data areaDATA, the pattern shown in FIG. 25 has a length of 3 bytes. This patternis preferable when the immediately preceding second synchronization areaVFO has repeated 4T recording marks/spaces. The pattern is described indetail in Japanese Patent No. 3098258.

FIG. 26 shows another example of a pattern to be recorded in the fourthsynchronization area PS (PS pattern), the example being especiallypreferable in the third example of the present invention. The patternshown in FIG. 26 is, in the NRZ representation, {00000 00000 10000 0000001000 00000 00100 00000 00010}. The pattern has 45 channel bits intotal. The pattern has the features of (i) including 11T recording marksand 11T spaces alternately repeated twice; and (ii) having an absolutevalue of DSV of as small as 1. When a run length limited code having theparameters of d=2, k=10, m=8, n=15 and r=1 is used for modulation of thedata area DATA, the pattern shown in FIG. 26 has a length of 3 bytes.This pattern is especially preferable when the post-modulation sequencedoes not include 11T recording marks or spaces repeated four times ormore, since this pattern provides a sufficient code distance from allthe types of patterns which can exist in the data area DATA and otherareas and is highly resistant against incorrect detection.

FIG. 27 shows still another example of a pattern to be recorded in thefourth synchronization area PS (PS pattern), the example beingespecially preferable in the third example of the present invention. Thepattern shown in FIG. 26 is, in the NRZ representation, {000 000 000 010000 001 000 000 100 000 000 001}. The pattern has 36 bits in total. Thepattern has the features of (i) including a pattern of 11T•7T•7T•11T and(ii) having a DSV of 0. When a run length limited code having theparameters of d=1, k=7, m=2, n=3 and r=1 is used for modulation of thedata area DATA, the pattern shown in FIG. 27 has a length of 3 bytes.This pattern is especially preferable because this pattern, whichincludes two patterns of (Tmax+3)=11T (Tmax is the maximum inversioninterval), provides a sufficient code distance between all the types ofpatterns which can exist in the data area DATA and other areas and thusis highly resistant against incorrect detection.

A method for recording data on the optical disc medium 401 having theabove-described data format is similar to the method described in thefirst example, and will not be described in detail.

FIG. 28 shows still another example of a pattern to be recorded in thefourth synchronization area PS (PS pattern), the example beingespecially preferable in the third example of the present invention. Thepattern shown in FIG. 28 is, in the NRZ representation,“000000000001000000000001000000000001000000000001”. The pattern has 48channel bits in total. The pattern has the features of (i) including 12Trecording marks and 12T spaces alternately repeated twice; and (ii)having a CDS of 0. When an 8/16 modulation system is used for the dataarea DATA, 12T, which is (Tmax+1) bits, does not exist in any data bitstream in the data area DATA. When the pattern of 12T recording marksand 12T spaces is repeated 4 times, the code distance between such apattern and the data bit stream obtained by the 8/16 modulation can besignificantly extended. Therefore, the pattern shown in FIG. 28 is veryhighly resistant against incorrect detection.

In the case where the immediately preceding second synchronization areaVFOa (FIG. 24) has a pattern of “0001000100010001 . . . ” in which 4Trecording marks and 4T spaces are repeated, the DSV value is maintainedat 0 from the start of the second synchronization area VFOa to thetermination position of the fourth synchronization area PS. Therefore,the slicing level for level-slicing of data performed by thereproduction apparatus can be stable. This is advantageous toreproducing the pattern recorded in the synchronization area SYaincluded in the immediately subsequent second frame area 502 a.

When the 8/16 modulation system is used, the pattern shown in FIG. 28has a length of 3 bytes. When a first frame area 501 a (FIG. 24) has alength of 93 bytes and the third synchronization code sequence PA has alength of 2 bytes, the second synchronization area VFOa (FIG. 24) has alength of 88 bytes.

FIG. 29 shows still another example of a pattern to be recorded in thefourth synchronization area PS (PS pattern), the example beingespecially preferable in the third example of the present invention. Thepattern shown in FIG. 29 is, in the NRZ representation,{000000001000000000000100000000000010000000010”. The pattern has 45channel bits in total. The pattern has the features of (i) including apattern of 9T•13T•13T•9T and (ii) having an absolute value of DSV of assmall as 1. When a run length limited code having the parameters of d=2,k=10, m=8, n=15 and r=1 is used for modulation of the data area DATA,the pattern shown in FIG. 29 has a length of 3 bytes.

This pattern includes a pattern having (Tmax+2) bits and a patternhaving (Tmax−2) bits which are each repeated twice. Therefore, as in thecase of the pattern shown in FIG. 28, the code distance between thepattern shown in FIG. 29 and the post-modulation data bit stream can besignificantly extended. Furthermore, the pattern shown in FIG. 29 is acombination of long recording marks/long spaces, but has an averageinversion interval, i.e., an edge required for phase comparisonperformed by the data PLL occurs every Tmax. This is equal to themaximum frequency at which the edge occurs, and thus there is no adverseinfluence by the edge not detected for a long period in the data PLL ofthe reproduction apparatus.

Since the long recording marks are ordered as(Tmax−2),(Tmax+2)·(Tmax+2)·(Tmax−2), a partial pattern can be detectedat a higher reliability. Instead of the entire pattern recorded in thefifth synchronization code sequence PS being detected by a method usingcomplete matching, only the first half of the pattern, i.e.,(Tmax−2)·(Tmax+2) can be detected, or only the second half of thepattern, i.e., (Tmax+2)·(Tmax−2) can be detected. The reason is thateven the first half or the second half can maintain a sufficient codedistance from all the types of patterns which can exist in the data areaDATA and the other areas. Accordingly, the pattern shown in FIG. 29 ishighly resistant against incorrect detection and is especiallypreferable.

FIG. 30 shows still another example of a pattern to be recorded in thefourth synchronization area PS (PS pattern). The pattern shown in FIG.30 is especially preferable when, for example, a run length limited codehaving parameters of d=1, k=7, m=2 and n=3 (so-called (1-7) modulationsystem) is used for modulation of the data area DATA.

The pattern shown in FIG. 30 is, in the NRZ representation,“00100000100000000100000000010000010”. The pattern has 36 channel bitsin total. The pattern has the features of (i) including a pattern of6T•10T•10T•6T and (ii) having a CDS of 0. According to a known (1-7)modulation system of transforming 8-bit binary data into a 12 bitchannel code word, the pattern shown in FIG. 30 has a length of 3 bytes.

Since the long recording marks are ordered as(Tmax−2)·(Tmax+2)·(Tmax+2)·(Tmax−2), a partial pattern can be detectedat a higher reliability. Instead of the entire pattern recorded in thefifth synchronization code sequence PS being detected by a method usingcomplete matching, only the first half of the pattern, i.e.,(Tmax−2)·(Tmax+2) can be detected, or only the second half of thepattern, i.e., (Tmax+2)·(Tmax−2) can be detected. The reason is thateven the first half or the second half can maintain a sufficient codedistance from all the types of patterns which can exist in the data areaDATA and the other areas. Accordingly, the pattern shown in FIG. 30 ishighly resistant against incorrect detection and is especiallypreferable.

FIG. 31 shows still another example of a pattern to be recorded in thefourth synchronization area PS (PS pattern). The pattern shown in FIG.31 is “1010010000000100000000001000000000001000000010010” in the NRZrepresentation. The pattern has 48 channel bits in total. The patternhas the feature of including a pattern of 8T•12T•12T•8T. The pattern ispreferable when a run length limited code having parameters of d=1, k=9,n/m=1.5 is used for modulation of the data area DATA. Like the patternshown in FIG. 30, this pattern includes(Tmax−2)·(Tmax+2)·(Tmax+2)·(Tmax−2) and thus is highly resistant againstincorrect detection. As a result of performing NRZI recording of a 8Trecording mark or space together with two 3T spaces or recording marksinterposing the 8T recording mark or space, the total length of therecording mark portions is equal to the total length of the spaceportions (where the CDS=0). The pattern shown in FIG. 31 is symmetricalin a circumferential direction. Therefore, even when the asymmetry (inwhich the amplitude of the recording mark portions and the amplitude ofthe space portions are asymmetric to each other; a well known phenomenonof reproduction signal degradation which is caused when a power forrecording data on the optical disc medium changes) occurs, the patternshown in FIG. 31 can be stably detected.

Since the pattern shown in FIG. 31 starts with 3T, the continuity at theconnection position is superior (easily fulfills the run lengthlimitation) when the pattern in the second synchronization area VFOimmediately preceding the fourth synchronization code sequence PS is(Tmin+1), i.e., a repetition of 3T.

As described above, the first frame area 501 corresponding to a linkingframe area includes a first synchronization area PA, a secondsynchronization area VFO and a fourth synchronization area PS. Due tosuch a structure, even when the length of a frame area changes due tovarious fluctuation error factors of a driving apparatus, the datarecorded in the second frame area 502 can be stably read. Thus, anoptical disc medium having a high resistance to error can be realizedwith minimum possible overhead. Thus, the reliability of thereproduction apparatus can be maintained high.

In the example shown in FIG. 24, the data block 403 a is not shown asincluding a sector. The data block 403 a can have a sector as describedabove with reference to FIG. 9. The leading frame area of each sectorand the other frame areas can have different synchronization codesequences (SY0 and SY) recorded therein, also as described above withreference to FIG. 9. In this case, the start of the sector or the datablock can be more easily detected, thus significantly improving thereliability of information recording reproduction.

As described above, in the third example of the present invention, theinformation track 402 of the optical disc medium 401 is divided intodata blocks 403 (403 a), each of which is a unit of recording andreproduction. Each data block 403 (403 a) includes a first frame area501 (501 a) located at the start thereof and at least one second framearea 502 located subsequent to the first frame area 501 (501 a). Eachfirst frame area 501 (501 a) includes a first synchronization area PA, asecond synchronization area VFO and a fourth synchronization area PS.Each second frame area 502 includes a third synchronization area SY anda data area DATA in which user data is to be recorded. Thebeginning/termination of data recording (linking) is performed in thesecond synchronization area VFO of the first frame area 501 a (linkingframe area). Therefore, even when the data is recorded in adiscontinuous manner, that discontinuity is absorbed in the secondsynchronization area VFO. In the third example of the present invention,a fourth synchronization area PS is located after the secondsynchronization area VFO of the first frame area 501 (501 a). In thefourth synchronization area PS, a PS pattern (fifth synchronization codesequence) for identifying the end of the VFO pattern is recorded.Identification of the end of the VFO pattern is equivalent to theIdentification of the end of the first synchronization code sequence(the portion 2102 in FIG. 1) described in the first example. Since thesynchronization information before and after the linking (data in thefirst synchronization area PA and the fourth synchronization area PS) isreinforced in this manner, data can always be reproduced stably. The PSpattern is used for specifying the start of the entirety of the at leastone second frame area (first area) in which the at least one secondframe (collectively referred to as first area data) is recorded (i.e.,for specifying the start of the recorded first area data). The firstarea is located rearward to the fourth synchronization area PS.

In the third example, the first frame area (first area and third area)includes a first synchronization area PA, a second synchronization areaVFO and a fourth synchronization area PS, but can include othersynchronization code sequences or data bit streams.

EXAMPLE 4

FIG. 32 shows a top view of a recordable optical disc medium 701according to a fourth example of the present invention. On a recordingsurface of the optical disc medium 701, a recording track 702 is formedin a spiral manner. The recording track 702 is divided into data blocks703. In other words, on the recording surface of the optical disc medium701, the data blocks 703 are continuously arranged in a circumferentialdirection to form the information track 702.

FIG. 33 shows a data format of the data blocks 703 of the optical discmedium 701 according to the fourth example of the present invention. Asshown in FIG. 33, a first frame area 801 is located at the start of eachdata block 703, and a plurality of second frame areas 802 are locatedsubsequent to the first frame area 801. The first frame area 801 and theplurality of second frame areas 802 form one data block 703. In FIG. 33,an area shown in the right is rearward to an area shown in the left.

The first frame area 801 includes a first synchronization area PA at thestart thereof, and a specific purpose data area DASP subsequent thereto.Each second frame areas 802 includes a third synchronization area SY atthe start thereof and a data area DATA subsequent thereto.

In the fourth example of the present invention, the firstsynchronization area PA, the third synchronization area SY, and the dataarea DATA have the same roles of those in the first example, and willnot be described in detail. The fourth example is different from thefirst example in that the specific purpose data area DASP is provided inthe first frame area 801 a which is located at the start of the ECCblock (the first frame area included in a leading data block 703 a ofthe ECC block), instead of located in the second synchronization areaVFO in the first frame area 201. The first frame area 801 of each of thedata blocks other than the leading data block of the ECC block can havea similar structure to that of the first frame area 801 a.

In the fourth example of the present invention, as shown in FIG. 33, anECC block 804 forming an error correction code includes four continuousdata blocks 703. An error correction code accounts only for the dataareas DATA included in the four continuous data blocks 703, and does notaccount for the specific purpose data area DASP.

In the specific purpose data area DASP, a data bit stream includingspecific purpose data having a different use from that of the user dataincluded in the data area DATA is recorded. The data recorded in thespecific purpose data area DASP can be treated as being independent fromthe data recorded in the data area DATA. Therefore, reading of the datarecorded in the specific purpose data area DASP does not require thedata recorded in the data area DATA in the same data block 703 to beread or error-corrected, etc.

At least one specific purpose data area DASP is provided in each datablock. A plurality of specific purpose data areas DASP are provided ineach ECC block. Therefore, in the specific purpose data area DASP, datarepresenting information corresponding to the respective data block orECC block (specific purpose data) can be recorded.

The specific purpose data area DASP can have, for example, the followinguses.

(Use 1) Data attribute of user data recorded in the data area DATA ofthe respective data block.

(Use 2) Information regarding a method for recording data or recordingcharacteristics of the respective data block.

Use 1 is for recording the attribute of the recorded user data on a datablock-by-data block basis. The attribute is obtained independently fromthe user data included in the data area DATA of the respective datablock. Accordingly, the attribute is obtained without reading the userdata. Therefore, when information on copyright protection, for example,is included as the attribute, control can be performed for copyrightprotection using each data block as a minimum unit.

Use 2 is for recording information regarding a method for recording dataor recording characteristics of the respective data block on a datablock-by-data block basis Such information is obtained independentlyfrom the user data included in the data area DATA of the respective datablock. Accordingly, the information is obtained without reading the userdata. Therefore, the information on a method for recording data orrecording characteristics of the respective data block can be used whenrecording data in the respective data block or the other data block.

One ECC block includes a plurality of data blocks. Data is overwrittenon a ECC block-by-ECC block basis. The first frame area 801 acorresponding to the start of each ECC block is used as a linking framearea. Due to such a structure, a plurality of specific purpose dataareas DASP can be located in one ECC block. It is effective to recordidentical specific purpose data in all the specific purpose data areasDASP included in one ECC block. In this manner, even when specificpurpose data recorded in one specific purpose data area DASP of thefirst frame area 801 a cannot be read because of overwriting and islost, the same specific purpose data recorded in another specificpurpose data area DATA can be read. Thus, the specific purpose data canbe reproduced safely.

FIGS. 34A and 34B show other examples of the structure of the firstframe area 801 a in the fourth example of the present invention.

In the example shown in FIG. 34A, the first frame area 801 a includes afirst synchronization area PA and a second synchronization area VFO. Inthe example shown in FIG. 34B, the first frame area 801 a includes afirst synchronization area PA, a second synchronization area VFO, and athird synchronization area PS.

In these examples, the second synchronization area VFO is provided onlyin the leading frame area (corresponding to the linking frame area) atthe start of each ECC block. Thus, the synchronization pattern requiredfor stabilizing the reproduction of data recorded on the optical discmedium 701 is reinforced (i.e., a pattern for guaranteeing thesynchronization at the time of reproduction is recorded). The specificpurpose data area DASP is located in the first frame area 801 at thestart of each of the data blocks other than the data block at the startof each ECC block. Accordingly, data can be read stably even at thebeginning/termination position of data recording. Moreover, specificpurpose data can be recorded or reproduced independently from the userdata in each ECC block.

In the examples shown in FIGS. 34A and 34B, the frame area at the startof each ECC block includes a second synchronization area VFO so as toreinforce the synchronization pattern. The present invention is notlimited to this. When data is recorded in a plurality of ECC blocks in aseries of data recording, the leading frame area of each of the secondand subsequent ECC blocks can have a specific purpose data area DASP,not the frame area having a synchronization pattern reinforced.

In the fourth example, the case where the first frame area (first areaand third area) includes a first synchronization area PA, a secondsynchronization area VFO and a fourth synchronization area PS, and thecase where the first frame area (first area and third area) includes afirst synchronization area PA and a specific purpose data area DASP aredescribed. The present invention is not limited to this. For example,the first frame area can include the fourth synchronization area PS whenincluding the specific purpose data area DASP, or other synchronizationcode sequences or data bit streams.

EXAMPLE 5

FIG. 35 shows a top view of a recordable optical disc medium 1001according to a fifth example of the present invention. On a recordingsurface of the optical disc medium 1001, a recording track 1002 isformed in a spiral manner. The recording track 1002 is divided into datablocks 1003 a and 1003 b. The information track 1002 is divided into aninner portion, an intermediately portion and an outer portion. The innerportion and the outer portion are each a reproduction-only area 1004used exclusively for reproduction. The intermediate portion is arewritable area 1005. Each data block 1003 a included in thereproduction-only area 1004 has pits already recorded therein. The pitsare formed using, for example, convex and concave portions of therecording surface. In each data block 1003 b included in the rewritablearea 1005, data is to be recorded by a recording apparatus.

FIG. 36 shows a data format of the data blocks 1003 a included in thereproduction-only area 1004 of the optical disc medium 1001 in the fifthexample of the present invention. As shown in FIG. 36, each data block1003 a includes a first frame area 1101 at the start thereof and aplurality of second frame areas 1102 located subsequent to the firstframe area 1101. The first frame area 1101 and the plurality of secondframe areas 1102 form one data block 1003 a. In FIG. 36, an area shownin the right is rearward to an area shown in the left.

The first frame area 1101 includes a first synchronization area PA atthe start thereof, and a specific purpose data area DASP subsequentthereto. Each of the second frame areas 1102 includes a thirdsynchronization area SY at the start thereof and a data area DATAsubsequent thereto. The first synchronization area PA, the thirdsynchronization area SY and a data area DATA have the same roles ofthose in the first example, and will not be described in detail. Thespecific purpose data area DASP has the same roles as those in thefourth example and will not be described in detail.

FIG. 37 shows a data format of the data blocks 1003 b included in therewritable area 1005 of the optical disc medium 1001 in the fifthexample of the present invention. As shown in FIG. 37, each data block1003 b has the same structure as that of the data block 1003 a. Eachdata block 1003 b includes a first frame area 1201 at the start thereofand a plurality of second frame areas 1202 located subsequent to thefirst frame area 1201. The first frame area 1201 and the plurality ofsecond frame areas 1202 form one data block 1003 b. In FIG. 37, an areashown in the right is rearward to an area shown in the left.

The first frame area 1201 includes a first synchronization area PA atthe start thereof, a second synchronization area VFO subsequent thereto,and a fourth synchronization area PS. The second frame area 1202includes a third synchronization area SY at the start thereof and a dataarea DATA located subsequent to the third synchronization area SY.

The first synchronization area PA, the second synchronization area VFO,the data area DATA and the third synchronization area SY have the sameroles as those of the first example and will not be described in detail.The fourth synchronization area PS has the same roles as those of thesecond example and will not be described in detail. The fourthsynchronization area PS may be optionally provided.

As shown in FIGS. 36 and 37, both the reproduction-only area 1004 andthe rewritable area 1005 are both divided into data blocks and havesimilar frame structures to each other. Therefore, reproduction steps atleast after a reproduction RF is obtained (level slicing of data, PLL,demodulation and the like) can be performed in almost the same manner inthe reproduction-only area 1004 and the rewritable area 1005 althoughthe two areas have data recorded in different physical shapes (i.e.,recorded by the convex and concave portions of the recording surface, orrecorded by the phase change of the recording layer). Accordingly, thereproduction apparatus need not include two different types ofreproduction circuits, i.e., a reproduction circuit for the reproductionareas and a reproduction circuit for the rewritable areas. Thus, thestructure of the reproduction circuit can be simplified, thus reducingthe cost of the reproduction apparatus.

The data block 1003 a included in the reproduction-only area 1004 andthe data block 1003 b included in the rewritable area 1005 are differentfrom each other in the internal structure of the first frame areas 1101and 1201 at the start thereof.

The first frame area 1201 of a leading data block of each ECC blockincluded in the rewritable area 1005 corresponds to a linking frame areaincluding the beginning/termination position of additional datarecording. As described in detail in the first example, when data isrecorded in a discontinuous manner at the beginning/termination position(linking frame area) of additional data recording, the subsequent datablocks need to be correctly reproduced. For this purpose, the firstframe area 1201 includes the first synchronization area PA, the secondsynchronization area VFO and the fourth synchronization area PS so as toreinforce the synchronization information. In addition, data recordingcan be begun and terminated in the second synchronization area VFO inwhich no user data is to be recorded.

The first frame area 1101 in the reproduction-only area 1004 correspondsto an overhead area in which no user data is to be recorded. In thisarea, data discontinuity does not occur since data is not rewritten.Therefore, in this area, data representing information corresponding tothe respective data block (specific purpose data), which can bereproduced independently from the user data, can be recorded. For thispurpose, the specific purpose data area DASP is provided after the firstsynchronization area PA, so that information which is reproduceableindependently from the user data can be recorded.

In the example shown in FIG. 35, the optical disc medium 1001 includesthe reproduction-only area 1004 and the rewritable area 1005. Theoptical disc medium 1001 can have only the reproduction-only area 1004.

As described above, in the optical disc medium 1001 in the fifth exampleof the present invention, the data blocks included in thereproduction-only area 1004 and the data blocks included in therewritable area 1005 have the same frame structure. This contributes toa reduction in the scale of the reproduction circuit of a drivingapparatus.

In the optical disc medium 1001 in the fifth example of the presentinvention, the first frame area 1101 in each data block in thereproduction-only area 1004, or the first frame area 1201 in a datablock in the rewritable area 1005 which is not a linking area, caninclude a specific purpose data area DASP instead of an area forreinforcing synchronization. Thus, information which can be treatedindependently from user data can be recorded or reproduced as specificpurpose data. For example, information on copyright protection,information which is inherent to each driving apparatus, or informationfor future application can be recorded or reproduced. This significantlycontributes to an expansion in the usage of optical disc media andrecording and reproduction apparatuses.

In the fifth example, the case where the first frame area (first areaand third area) includes a first synchronization area PA, a secondsynchronization area VFO and a fourth synchronization area PS, and thecase where the first frame area (first area and third area) includes afirst synchronization area PA and a specific purpose data area DASP aredescribed. The present invention is not limited to this. For example,the first frame area can include the fourth synchronization area PS whenincluding the specific purpose data area DASP, or other synchronizationcode sequences or data bit streams.

EXAMPLE 6

FIG. 38 shows a structure of an information recording apparatus(recording apparatus) 1710 according to a sixth example of the presentinvention. The information recording apparatus 1710 records informationon, for example, the optical disc medium 101 (FIG. 1), the optical discmedium 3101 (FIG. 8), the optical disc medium 401 (FIG. 23) or theoptical disc medium 1001 (FIG. 35). In the following description, theinformation recording apparatus 1710 records information on the opticaldisc medium 3101 described in detail in the second example.

A recording and reproduction head 1701 records data on the optical discmedium 3101, or reads data pre-recorded on the optical disc medium 3101or data recorded on the optical disc medium 3101 by an apparatus.

The recording and reproduction head 1701 includes, for example, a lightsource (for example, a semiconductor laser) for optically recording asignal, a driving circuit for driving the light source in correspondencewith recording data WTDT, an optical system for collecting light emittedby the light source on a recording surface of the optical disc medium3101 or detecting light reflected by the optical disc medium 3101 andreading the light as a signal, and an opto-electric converter forreproducing a read signal as an electric signal RF.

A signal level-slicing section 1702 amplifies the signal RF read by therecording and reproduction head 1701 and level-slices the signal RF bynecessary processing.

A pattern detection and synchronization section 1703 detects asynchronization code sequence in conformity with the data format of theoptical disc medium 3101 using level-sliced data RDDT obtained by thesignal level-slicing section 1702, and identifies the positioninformation of data which is being read by the recording andreproduction head 1701 in real time. The detailed internal operation ofthe pattern detection and synchronization section 1703 will be describedlater.

A timing control section 1704 controls the operation of an ECC encodingsection 1705 and a modulation section 1706 so that data to be recordedis recorded at a prescribed position of the optical disc medium 3101based on position information ADR obtained by the real-timeidentification performed by the pattern detection and synchronizationsection 1703. In addition to the control operations for recording, thetiming control section 1704 also performs a search operation for movingthe recording and reproduction head 1701 using the position informationADR so that the signal can be read or recorded at a prescribed positionof the optical disc medium 3101.

The ECC encoding section 1705 adds redundant data such as an errorcorrection code or the like to the user data to be recorded which isinput from the outside of the information recording apparatus 1710 andencodes the resultant data into a prescribed format. The ECC encodingsection 1705 also outputs the encoded data ECCDT to the modulationsection 1706 based on a recording operation timing signal WTGT from thetiming control section 1704. The ECC encoding section 1705 acts as areceiving section for receiving user data from the outside of theinformation recording apparatus 1710.

The modulation section 1706 receives the data ECCDT encoded by the ECCencoding section 1705, modulates the data ECCDT using a prescribedmodulation system, and outputs the obtained data to the recording andreproduction head 1701 as recording data WTDT.

The information recording apparatus 1710 in the sixth example of thepresent invention records information on the optical disc medium 3101 bycooperation and association of the above-described elements. In order toadditionally record data located subsequent to the data block in whichdata is already recorded (linking), precise recording needs to beperformed to the data already recorded.

It is important that the information recording apparatus 1710 shouldcorrectly detect the position of the data already recorded and operatein precise synchronization therewith. For this purpose, an operation ofdetecting various synchronization code sequences described in detail inthe second example using the level-sliced data reproduced by therecording and reproduction head 1701 and the level-slicing section 1702so as to obtain correct position information, i.e., the operation of thepattern detection and synchronization section 1703, is most important.The position information ADR includes, for example, a sector positionSPt, a frame position FPt, and a byte position BPt.

FIG. 39 shows an example of an internal structure of the patterndetection and synchronization section 1703, which includes the followingelements.

An SY0 pattern detection section 1901 detects an SY0 pattern from thelevel-sliced data RDDT and outputs an SY0 detection signal SY0DET. TheSY0 pattern detection section 1901 acts as a first detection section fordetecting the SY0 pattern (second synchronization code sequence).

A PA pattern detection section 1902 detects a PA pattern from thelevel-sliced data RDDT and outputs a PA detection signal PADET. The PApattern detection section 1902 acts as a third detection section fordetecting the PA pattern (third synchronization code sequence).

An SY pattern detection section 1903 detects an SY pattern from thelevel-sliced data RDDT and outputs an SY detection signal SYDET.

A 1-frame timer 1904 identifies the byte position from the start of eachframe area and outputs a byte position signal BPt and a framesynchronization pulse FRMPLS reflecting the identification results inreal time. The 1-frame timer 1904 includes, for example, a firstcounting section (not shown) for counting the number of bytes (93 bytes)or the number of channel bits (1488 channel bits in the case of the 8/16modulation system) in one frame area, and a byte position detectionwindow generation section (not shown) for generating a detection windowfor a synchronization code sequence. The 1-frame timer 1904 receives thedetection signals SY0DET, PADET, and SYDET respectively from the patterndetection sections 1901 through 1903 and adjusts the built-in firstcounting section while appropriately controlling the detection window bythe built-in byte position detection window generation section forpreventing a synchronization shift from being caused by an incorrectdetection of the pattern. The counting value obtained by the firstcounting section (representing the byte position of the start of theframe area) is output as a byte position signal BPt, and a framesynchronization pulse FRMPLS is output at a prescribed byte positiononce in one frame (about every 93 bytes).

The 1-frame timer 1904 basically predicts the position of asynchronization code sequence based on the pattern detection result ofthe immediately preceding synchronization code sequence, and opens thedetection window during a time period in which the synchronization codesequence is expected to be detected. When a detection signal for thesynchronization code sequence is received during this time period, the1-frame timer 1904 determines that the correct synchronization codesequence is detected and presets the counting value BPt of the firstcounting section to a prescribed value. The preset value is notnecessarily 0, but is determined in consideration of the time delayrequired for detection.

The number of bytes in each frame is equal among the frames. Therefore,the byte position detection window generation section controls thedetection window to open for a prescribed time period every prescribedbyte cycle (specifically, about every 93 bytes, which is the number ofbytes in the frame area). The width of the detection window can bedetermined in consideration of all the fluctuation factors regardingsignal reading performed by the recording and reproduction head 1701(for example, a jitter component generated by rotation fluctuation,deflection or the like of the optical disc medium 3101, or datadiscontinuity in the linking frame area).

A frame counter 1905 identifies a frame position in each sector, andoutputs a frame position signal FRt and a sector synchronization pulseSCTPLS reflecting the identification results in real time. The framecounter 1905 includes, for example, a second counting section (notshown) for counting the number of frames (26 to 27 frames) in onesector, and a frame position prediction window generation section (notshown) for generating a prediction window for a first synchronizationcode sequence SY0 and a third synchronization code sequence PA. Theframe counter 1905 receives the frame synchronization pulse FRMPLS fromthe 1-frame timer 1904 and counts up the built-in second countingsection. The frame counter 1905 also receives the detection signalsSY0DET and PADET from the respective pattern detection sections, andadjusts the built-in second counting section while appropriatelycontrolling the prediction window by the built-in frame positionprediction window generation section for preventing a synchronizationshift from being caused by an incorrect detection of the pattern.

The frame position prediction window generation section generates aprediction window for each of an SY0 pattern and a PA pattern inconsideration of the order in which these patterns occurs. As describedin detail in the second example, each synchronization code sequence isdetected only in a prescribed order. For example, the secondsynchronization code sequence SY0 is detected once in one sector (oncein 26 frame areas; or once in 27 frame areas where the first frame area201 (FIG. 9) is included). Utilizing this, the frame position predictionwindow generation section can generate a prediction window for eachsynchronization code sequence.

When the detection signal SY0DET is output while the prediction windowfor the SY0 pattern is open, the frame counter 1905 presets the countingvalue FPt of the second counting section to 0. When the detection signalPADET is output while the prediction window for the PA pattern is open,the frame counter 1905 presets the counting value FPt of the secondcounting section to 26. Unless a detection signal is output, thecounting value FPt of the second counting section is incremented by oneeach time the frame synchronization pulse FRMPLS is output. In thismanner, the counting value of the built-in second counting section isoutput as a frame position signal FPt, and a sector synchronizationpulse SCTPLS is output at a prescribed frame position once in one sector(every 26 to 27 frame areas).

A sector counter 1906 identifies a sector position in each data block,and outputs a sector position signal SPt reflecting the identificationresults in real time. The sector counter 1906 includes, for example, athird counting section (not shown) for counting the number of sectors (8sectors) in one data block, and a sector position prediction windowgeneration section (not shown) for generating a prediction window forthe third synchronization code sequence PA. The sector counter 1906receives the sector synchronization pulse SCTPLS from the frame counter1905 and counts up the built-in third counting section. The sectorcounter 1906 also receives the detection signal PADET from the PApattern detection section 1902, and adjusts the built-in third countingsection while appropriately controlling the prediction window by thebuilt-in sector position prediction window generation section forpreventing a synchronization shift from being caused by an incorrectdetection of the pattern.

The sector position prediction window generation section generates aprediction window for the PA pattern in consideration of the order inwhich the PA pattern occurs. As described in detail in the secondexample, the third synchronization code sequence PA occurs only once in8 sectors. The sector prediction window generation section can generatea prediction window utilizing this.

When the detection signal PADET is output while the prediction windowfor the PA pattern is open, the sector counter 1906 presets the countingvalue SPt of the third counting section to 0. Unless a detection signalPADET is output, the counting value SPt of the third counting section isincremented by one each time the sector synchronization pulse SCTPLS isoutput. In this manner, the counting value of the built-in third sectionis output as a sector position signal SPt.

The pattern detection and synchronization section 1703 having theabove-described internal structure detects each synchronization codesequence (pattern) included in the data format described in detail inthe second example, using level-sliced data RDDT which is read from theoptical disc medium 3101. Thus, the position information of the readingdata, i.e., the sector position SPt, the frame position FPt, and thebyte position BPt are obtained in real time. Using such positioninformation which is output from the pattern detection andsynchronization section 1703, the timing control section 1704 (FIG. 38)can generate and output a recording operation timing signal WTGT whichinstructs at least the ECC encoding section 1705 to perform a recordingoperation.

The internal structure shown in FIG. 39 is merely an example. Theinternal structure of the pattern detection and synchronization section1703 is not limited to this. In the example shown in FIG. 39, an SY0pattern, an SY pattern and a PA pattern are used as synchronization codesequences to be detected. A PS pattern described in the third examplecan additionally be used. In this case, the number of patterns to bedetected is increased, and therefore the synchronization performance andthe position information identification performance are improved. Thiswill be described below with reference to FIG. 40.

All the position information in the optical disc medium 3101 cannot beidentified only with four types of synchronization code sequences. Withthe four types of synchronization code sequences, the sector position,the frame position and the byte position in each data block can beidentified but the position of the data block currently read in anoptical disc medium cannot be identified. In order to identify theposition of the data block currently read, ID information is necessary.For example, the data position identification area DataID shown in FIG.14 is used for that purpose.

FIG. 40 shows another example of an internal structure of the patterndetection and synchronization section 1703, which includes the followingelements. The internal structure shown in FIG. 40 is different from theinternal structure shown in FIG. 39 in that a PS pattern detectionsection 2001 is further included. Identical elements and identicalinternal signals transmitted between the elements as those describedabove with reference to FIG. 39 bear corresponding reference numeralsthereto and will not be described in detail.

As described in the third example, a PS pattern is located at the end ofthe first frame area 501 a, which is the linking position, for thepurpose of improving the reliability of detecting the start of each datablock. When the data block includes sectors, the first frame area 501 ais necessarily located immediately before the second frame area at thestart of the sector. Therefore, the PS pattern can also be used for thepurpose of improving the reliability of detecting the start of eachsector. Since the PS pattern is located at the end of the first framearea 501 a, the PS pattern can also be used for the purpose of improvingthe reliability of detecting the start of each frame area. The PSpattern detection section 2001 acts as a fourth detection section fordetecting the PS pattern (fifth synchronization code sequence).

For the above-described reasons, an output PSDET from the PS patterndetection section 2001, which is a detection result of the PS pattern,is input to a 1-frame timer 2002, a frame counter 2003, and a sectorcounter 2004, and is used for position identification in each of thecounters.

FIG. 41 shows the relationship between the data format of the opticaldisc medium 3101 and the position information. In FIG. 41, the firstframe area is represented by “LF”. The first frame area is representedas having the fourth synchronization area PS described in the thirdexample. FIG. 41 shows exemplary values of the position information,i.e., the sector position signal SPt, the frame position signal FPt, andthe byte position signal BPt, in the state where the synchronization isestablished.

The sector position signal SPt takes values of 0 through 7 sequentiallyfrom the leading sector of each data block. In the first frame area LFat the start of the data block, the sector position signal SPt is 0.

The frame position signal FPt takes values of 0 through 25 sequentiallyfrom the leading sector of each sector, although the value of the frameposition signal FPt is 26 in the first frame area LF. In all the sectorsincluded in each data block, the value of the frame position signal FPtof each of the frame areas (F0 through F25) is in the range of 0 through25.

The byte position signal BPt has a value of 0 through 92 sequentiallyfrom the leading sector of each frame area. In all the frame areasincluded in each sector, the value of the byte position signal BPt is 0at the start of the frame area. The value of the byte position signalBPt when passing through any of the SY0 pattern, the SY pattern, or thePA pattern is 0 or 1.

FIG. 41 also shows an exemplary waveform of a recording operation timingsignal WTGT generated by the timing control section 1704 using theposition information (position signals SPt, FPt and BPt). The recordingoperation timing signal WTGT shown in FIG. 41 is for recording data inone ECC block, i.e., four continuous data blocks. The recordingoperation timing signal WTGT represents a recording operation when beingat a HIGH level. At this point, the ECC encoding section 1705 outputsECC-encoded data ECCDT to the modulation section 1706.

The additional data recording is performed in the first frame area whichis a linking frame area. In other words, the beginning/termination ofdata recording is always performed in the second synchronization areaVFO of the first frame area. Therefore, the recording operation timingsignal WTGT changes from the LOW level to the HIGH level (beginning ofrecording) at the Sth byte counted from the start of the first framearea LF (S=8 in the example shown in FIG. 41) at the start of the datablock which is at the start of the ECC block. The recording operationtiming signal WTGT changes from the HIGH level to the LOW level(termination of recording) at the Eth byte counted from the start of thefirst frame area LF (E=11 in the example shown in FIG. 41) at the startof the next ECC block.

When proper synchronization is performed, in the first frame area LF,SPt=0 and FPt=26. Accordingly, the recording operation timing signalWTGT is preferably controlled so as to be at a HIGH level when {SPt=0,FPt=26 and BPt=S} in the current ECC block (in which the data is beingrecorded) and so as to be at a LOW level when {SPt=0, FPt=26 and BPt=E}in the next ECC block.

Thus, the pattern detection and synchronization section 1703 acts as adetection section for detecting a PA pattern (third synchronization codesequence). The timing control section 1704 acts as a determinationsection for determining the recording beginning position based on thestart of the detected PA pattern. As described above with reference toFIG. 2, the timing control section 1704 can determine the recordingbeginning position randomly each time recording is performed.

The ECC encoding section 1705, the modulation section 1706 and therecording and reproduction head 1701 together act as a recording sectionfor performing a recording process. As described above with reference toFIG. 2, the recording process includes a step of recording the recordstart VFO portion 2102 (first additional synchronization code sequenceused for stably reproducing data) (FIG. 2), a step of recording a secondframe, a step of recording a PA pattern, and a step of processing therecord finish VFO portion 2101 (fourth additional synchronization codesequence used for stably reproducing data) in the VFO pattern (FIG. 2).In the case where the optical disc medium has a data format described inthe third example, the recording process includes a step of recording aPS pattern.

During the recording operation, each synchronization code sequence isnot detected (or controlled not to be detected). Therefore, eachposition signal (SPt, FPt, BPt) is not preset and interpolation iscontinued.

As described above, the information recording apparatus 1710 includesthe pattern detection and synchronization section 1703 for detecting anSY0 pattern and a PA pattern from the pre-recorded data whenadditionally recording data to the information which is pre-recorded onthe optical disc medium (linking) or overwriting data. The informationrecording apparatus 1710 also includes the timing control section 1704for determining the timing for beginning recording of additional datausing the result of pattern detection. Due to such a structure,information can be additionally recorded or overwritten while detectingthe start of the first data unit (sector) or the second data unit (datablock) where data is pre-recorded at a high speed and stably. Thus, theinformation recording apparatus obtains a significantly improvedpositional precision of recording and thus an enhanced reliability.

Accordingly, the information recording apparatus 1710 providessignificant effects when applied to a large capacity, high speed datastorage device, video disc recorder, and multimedia recorder.

EXAMPLE 7

FIG. 42 shows a structure of an information reproduction apparatus(reproduction apparatus) 1810 according to a seventh example of thepresent invention. The information reproduction apparatus 1810reproduces information recorded on, for example, the optical disc medium101 (FIG. 1), the optical disc medium 3101 (FIG. 8), the optical discmedium 401 (FIG. 23) or the optical disc medium 1001 (FIG. 35). In thefollowing description, the information reproduction apparatus 1810reproduces information recorded on the optical disc medium 3101described in detail in the second example. In FIG. 42, the signallevel-slicing section 1702 and the pattern detection and synchronizationsection 1703 are identical with those described above with reference toFIG. 38 and will not be described in detail.

A reproduction head 1801 reads data recorded on the optical disc medium3101. The reproduction head 1801 includes, for example, a light sourcefor irradiating the optical disc medium 3101 with light (for example, asemiconductor laser), an optical system for detecting light reflected bya recording surface of the optical disc medium 3101 and reading thelight as a signal, and an opto-electric converter for reproducing readsignal as an electric signal RF.

A PLL section 1802 uses level-sliced data RDDT obtained by the signallevel-slicing section to reproduce a bit synchronization clock RDCLK inphase synchronization with the position of an edge of the level-sliceddata RDDT.

A demodulation section 1804 demodulates reproduction data using thelevel-sliced data RDDT and bit synchronization clock RDCLK and outputsthe post-demodulation data DEMDT.

A timing control section 1803 outputs a demodulation operation timingsignal RDGT to the demodulation section 1804 so that data recorded at aprescribed position of the optical disc medium 3101 can be reproducedbased on position information ADR obtained by the real-timeidentification performed by the pattern detection and synchronizationsection 1703. The demodulation operation timing signal RDGT represents ademodulation operation of reproduction data when being at a HIGH level.The demodulation section 1804 outputs post-demodulation signal DEMDTonly when the RDGT is at a HIGH level.

The timing control section 1803 outputs a level-slicing control timingsignal SLGT for controlling the mode of level slicing to the signallevel-slicing section 1702.

The level-slicing control timing signal SLGT represents a usuallevel-slicing operation mode when being at a HIGH level. The signallevel-slicing section 1702 controls the level-slicing level using areproduction signal RF when the SLGT is at a HIGH level. When the SLGTis at a LOW level, the signal level-slicing section 1702 holds thelevel-slicing level to the value at the time when SLGT is at a HIGHlevel and does not perform control.

The timing control section 1803 outputs a PLL control timing signalPLLGT for controlling the mode of PLL phase comparison to the PLLsection 1802. The PLL control timing signal PLLGT represents a usualPLL-following mode when being a HIGH level. When the PLLGT signal is ata HIGH level, the PLL section 1802 controls the built-in PLL to bephase-locked to the level-sliced data RDDT. When the PLLGT signal is ata LOW level, the PLL section 1802 holds the PLL and does not performcontrol.

In addition to the control operations for reproduction, the timingcontrol section 1803 also performs a search operation for moving thereproduction head 1801 using the position information ADR so that thesignal can be read at a prescribed position of the optical disc medium3101.

An ECC decoding section 1805 retrieves necessary data from thedemodulated data DEMDT, corrects the retrieved data using an errorcorrection code as necessary when an error is detected, and outputs theresultant data as user data.

The reproduction head 1801, the signal level-slicing section 1702, thePLL section 1802, the demodulation section 1804 and the ECC decodingsection 1805 together act as a reproduction section for reproducingvarious synchronization signals recorded in a synchronization area ofthe optical disc medium 3101 and at least a portion of user datarecorded in the data area DATA.

The information reproduction apparatus 1810 reproduces informationrecorded on the optical disc medium 3101 by cooperation and associationof the above-described elements. It is important that the informationreproduction apparatus 1810 should correctly detect the position of thedata already recorded on the optical disc medium 3101 having the dataformat described in the second example and operate in precisesynchronization therewith. For this purpose, an operation of detectingvarious synchronization code sequences described in detail in the secondexample using the level-sliced data reproduced by the reproduction head1801 and the level-slicing section 1702 so as to obtain correct positioninformation, i.e., the operation of the pattern detection andsynchronization section 1703, is most important. The operation of thepattern detection and synchronization section 1703 is described above indetail with reference to FIGS. 39 and 40 and will not be described indetail.

FIG. 43 shows operating waveforms of various timing signals used forreproducing data recorded in and in the vicinity of the first frame areaLF corresponding to the linking frame. The level-sliced control timingsignal SLGT changes from a HIGH level to a LOW level at the BR1st bytecounted from the start of the first frame area LF, and changes from aLOW level to a HIGH level at the BR2nd byte counted from the start ofthe first frame area LF. The PLL control timing signal PLLGT changesfrom a HIGH level to a LOW level at the BR1st byte counted from thestart of the first frame area LF, and changes from a LOW level to a HIGHlevel at the BR3rd byte counted from the start of the first frame areaLF, like the level-sliced control timing signal SLGT.

The demodulation operation timing signal RDGT is controlled in variousmanners depending on whether the immediately preceding data block is tobe demodulated or not. When the immediately preceding data block isdemodulated, the demodulation operation timing signal RDGT is at a HIGHlevel (as shown in FIG. 43 by dashed line), but changes from the HIGHlevel to a LOW level in the first frame area LF, at or before the BR1stbyte counted form the start of the first frame area LF. Then, at orafter the BR4th byte counted from the start of the first frame area LF,the demodulation operation timing signal RDGT is changed from the LOWlevel to a HIGH level. When the immediately preceding data block is notdemodulated, the demodulation operation timing signal RDGT is already ata LOW at the start of the first frame area LF (as shown in FIG. 43 bysolid line).

Here, it is assumed that the termination position of recording is theEth byte counted from the start of the first frame area LF, thebeginning position of recording is the 5th byte counted from the startof the first frame area LF (S and E are rational numbers less than 93bytes and fulfill S≦E), and the length of the third synchronization codesequence PA is 2 bytes. The values of BR1, BR2, BR3 and BR4 aredetermined so as to fulfill 2≦BR1<S, E<BR2<BR3<BR4<93.

In other words, by setting the level-slicing control timing signal SLGTto a LOW level at least from the Eth byte counted from the start of thefirst frame area LF to the 5th byte counted from the start of the firstframe area LF, the level-slicing level is held so as not to follow thereproduction signal RF in a portion where the quality of thereproduction signal RF is possibly inferior. The PLL control timingsignal PLLGT is at a LOW level for at least a portion where SLGT=LOW,like the level-slicing control timing signal SLGT. However, the point atwhich the PLL control timing signal PLLGT changes from the LOW level toa HIGH level is set rearward with respect to the point at which thelevel-slicing control timing signal SLGT is changed. Thus, thelevel-slicing control timing signal SLGT is held without PLL control ina portion where the quality of the reproduction signal RF is possiblyinferior, and after the operation of following the level-slicing isstarted, phase comparison between the PLL and the level-sliced data RDDTis resumed. The demodulation operation timing signal RDGT is set to beat a LOW level at least for a portion where PLLGT=LOW, like the PLLcontrol timing signal PLLGT. However, the point at which thedemodulation operation timing signal RDGT changes from the LOW level toa HIGH level is set rearward with respect to the point at which the PLLcontrol timing signal PLLGT is changed. Thus, the demodulation operationis not performed in a portion where the quality of the reproductionsignal RF is possibly inferior.

By setting the various timing signals as described above, even when datarecorded in and in the vicinity of the first frame area LF (linkingarea) is reproduced, the data discontinuity caused by linking or thedegradation in the recording layer caused by overwriting data many timesis prevented from influencing the reproduction processing system of theinformation reproduction apparatus. Thus, data can be correctlyreproduced.

The reproduction apparatus 1810 reproduces the specific purpose datarecorded in the reproduction area of the optical disc medium 1001 (FIG.35) as follows. A PA pattern (further third pattern) recorded in thefirst synchronization area PA in the first frame area 1101 (FIG. 36) isdetected by the PA pattern detection section 1902 (detection section).In response to the detection, the specific purpose data (specificpurpose data) recorded in the specific purpose data area DASP isreproduced.

Thus, the reproduction apparatus 1810 includes the pattern detection andsynchronization section for detecting the second synchronization codesequence (SY0 pattern) and the third synchronization code sequence (PApattern) and also the timing control section and the demodulationsection for determining the timing for beginning the reading operationof information using the pattern detection result. Due to such astructure, the reproduction apparatus 1810 can reproduce informationwhile detecting the start of the first data unit (sector) or the seconddata unit (data block) at a high speed and stably. Thus, the informationreproduction apparatus 1810 can reproduce data at a high speed andstably.

The timing control section 1704 and the signal level-slicing signal 1702together act as a level-slicing mode switching section for switching thelevel-slicing mode of a reproduction signal during a prescribed periodof the first frame area LF using the pattern detection result. Thetiming control section 1704 and the PLL section 1802 together act as aclock reproduction mode switching section for reproducing a clock in bitsynchronization with the reproduction signal. Due to such a structure,even when data is discontinuous or the quality of the reproductionsignal is degraded at the linking position, information recorded in andin the vicinity of the linking position can be reproduced stably. As aresult, the information reproduction apparatus 1810 has a significantlyenhanced reliability of information reproduction.

Accordingly, the information reproduction apparatus 1810 providessignificant effects when applied to a large capacity, high speed datastorage device, video disc recorder, and multimedia recorder.

In the above-described seven examples, an optical disc medium is used asan information recording medium according to the present invention. Thepresent invention is not limited to an optical disc medium. The presentinvention is applicable to, for example, a magnetic recording mediumsuch as a hard disc. None of the above-described examples limits thepresent invention. The present invention is only limited by the claims.

The recording medium according to the present invention is not limitedto either a medium having data pre-recorded or a medium having no datarecorded. Data may be pre-recorded in the entirety of the informationtrack of the recording medium, or the recording medium may have no datarecorded. The recording medium may have an area in which data ispre-recorded and an area in which no data is recorded.

INDUSTRIAL APPLICABILITY

In a recording medium according to the present invention, a recordingarea includes a first area and a second area. The area includes a framearea. In the frame area, a second synchronization code sequence and atleast a portion of data are recorded. The second area includes an areain which a third synchronization code sequence and a fourthsynchronization code sequence are to be recorded. On such a recordingmedium, additional data recording (linking) can be performed with aposition in the fourth synchronization code sequence as the beginningposition. Thus, additional data recording is not performed in the framearea in which data is recorded. Therefore, data recording andreproduction can be stably performed even at the beginning position andtermination position of the data recording.

1. A recording medium comprising a recording area, wherein: therecording area includes a first area, the first area includes a fourtharea including N number of frame areas, N being equal to or greater than2, each of the N number of frame area includes an area in which asynchronization code sequence and at least a portion of data arerecorded, the synchronization code sequence which is recorded in theframe area located at the start of the fourth area is different by acode distance equal to or greater than 2 in the NRZI representation fromany synchronization code sequence which is recorded in any of the frameareas other than the frame area located at the start of the fourth area,and the first area forms a unit of an error correction code.
 2. Arecording method for recording information on the recording mediumaccording to claim 1, the recording method comprising: generating andrecording on the recording medium the first area.
 3. A reproducingmethod for reproducing information recorded on the recording mediumaccording to claim 1, the reproducing method comprising: reproducing thesynchronization code sequence which has been recorded in the frame arealocated at the start of the fourth area; and reproducing at least theportion of the data.